LIBRARY 

OF    THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


WORKS  OF  ALFRED  I.  COHN 

PUBLISHED  BY 

JOHN  WILEY  &  SONS. 


Indicators  and  Test-papers. 

Their  Source,  Preparation,  Application,  and  Tests  for 
Sensitiveness.  With  Tabular  Summary  of  the  Applica- 
tion of  Indicators.  Second  Edition.  Revised  and  En- 
larged, lamo,  ix--(- 267  pages.  Cloth,  $2.00. 

Tests  and  Reagents, 

Chemical  and  Microscopical,  known  by  their  Authors' 
Names:  together  with  an  Index  of  Subjects.  8vo,  iii-f-383 
pages.  Cloth,  $3.00. 

TRANSLATION. 
Fresenius'  Quantitative  Chemical  Analysis. 

New  Authorized  Translation  of  the  latest  German 
Edition.  In  two  volumes.  By  Alfred  I.  Cohn. 
Recalculated  on  the  basis  of  the  latest  atomic  weights, 
and  also  greatly  amplified  by  the  translator.  8vo,  2  vols., 
upwards  of  2000  pages,  280  figures.  Cloth,  $12.50. 

Techno-Chemical  Analysis. 

By  Dr.  G.  LUNGC,  Professor  at  the  Eidgenbssische 
Polytechnische  Schule,  Zurich.  Authorized  Translation 
by  Alfred  I.  Cohn.  i2mo,  vii  +  136  pages,  16  figures. 
Cloth,  $1.00. 


TECHNO -CHEMICAL   ANALYSIS. 


BY 

DR.   G.' LUNGE, 

Professor  at  the  "Eidgenossische  Polytechnische  Schule"  at  Zurich. 


AUTHORIZED    TRANSLATION 

BY 

ALFRED   I.    COHN, 

Author  of  "Indicators  and  Test-papers,"  "  Tests  and  Reagents,"  " Freseniitf 

Quantitative  Analysis'"  (translation);  Member  of  American  Chemica' 

Society;  Society  of  Chemical  Industry;  etc. 


FIRST    EDITION. 


NEW  YORK : 

JOHN  WILEY   &   SONS. 
LONDON:  CHAPMAN  &  HALL,  LIMITED. 

1905. 
RA 

Of  THE 

UNIVERSITY 


•-V»3Al 


Copyright,  1904, 

BT 

ALFRED  I.  COHN. 


Entered  at  Stationers'  Hall. 


ROBERT  DRCMMOND,   PRINTER,  NEW  YORK. 


TABLE   OF  CONTENTS. 


PAGE 

I.  Scope  of  techno-ehemical  analysis I 

II.  General  operations  preceding  the  analysis. 3 

Taking  the  average  sample 3 

Comminuting ;  Weighing  off 4 

Measuring 5 

Sampling  gases , .  5 

III.  Technical  Gas-analysis 7 

1.  Winkler's  burette 7 

2.  Bunte's  burette 9 

3.  Orsat's  apparatus 12 

4.  Hem  pel's  burette 12 

Determining  gases  by  combustion , 19 

a.  By  explosion 20 

$.  With  the  palladium-asbestos  capillary  tube. ...  21 
c.   Combustion  of  methane  in  a  Drehschmidt  plat- 
inum capillary 22 

Reich's  method  of  determining  absorbable  gases  titri- 

metrically 23 

Determining  carbonic  acid  in  the  air 26 

Determining  very  small  quantities  of  gases  by  absorp- 
tion    26 

IV.  Gas-volumetry 27 

1.  The  azotometer 27 

2.  The  calcimeter 29 

3.  The  nitrometer  and  gas- volumeter 30 

iii 

141363 


iv  TABLE  OF  CONTENTS. 


SPECIAL  PART. 

PAGH 

Fuels  and  Heating 37 

Calorimeter , 37 

Examination  of  coal 38 

Gas-calorimeter 38 

Upper  and  lower  heat  values 38 

Smoke-gases  39 

Water 39 

Hardness.  Determining  by  Clark's  method 41 

Examination  by  purely  chemical  methods 41 


INORGANIC   CHEMICAL  MANUFACTURES. 

Sulphurous  and  sulphuric  acids 44 

Sulphur 44 

Gas-sulphur 45 

Pyrites 45 

Zinc  blende 47 

Cinders 47 

Calcination  gases 48 

Nitrose 48 

Lyes  for  sulphite  cellulose 49 

Sulphuric  acids  of  different  strengths 49 

Specific-gravity  table ...  '50 

Titration 50 

Impurities 52 

Fuming  sulphuric  acid. . : , 54 

Nitric  Acid  . . . . , 55 

Saltpeter 55 

Specific-gravity  table , . .  58 

Mixed-  and  waste-acids 59 

Titration 59 

Sulphate 59 

Common  table  salt 59 

Sulphate 60 

Hydrochloric  Acid 60 

Specific-gravity  table 61 


TABLE  OF  CONTENTS.  V 

PAGE 

Soda 62 

Eaw  materials 62 

Crude  soda-ash  melt 62 

Crude  lyes 62 

Carbonated  lyes 62 

Leach  residues 63 

Ammonia  soda 63 

Caustic  lyes 63 

Calcined  soda .' 64 

Crystal  soda 65 

Caustic  soda ;  Bicarbonate 65 

Chlorine  Industry 66 

Manganese  dioxide 66 

Limestone  ;  caustic  lime 67 

Chlorine  gas 68 

Electrolytic  lyes;  Bleaching  liquids 68 

Chlorinated  lime 69 

Potassium  Salts 71 

Crude  salt  (Carnallit,  Kainit,  etc.) 71 

Commercial  potassium  chloride 72 

Potash 72 

Potassium  cyanide;  Potassium  ferrocyanide 73 

Clay  and  Cement  Industry 74 

Clay  for  brick  manufacture  and  use  in  pottery 74 

Clay  and  marl  for  cements;  Cements 75 

Aluminium  sulphate 75 

Artificial  Manures 77 

1.  Phosphoric  acid , . . .  77 

2.  Nitrogen 79 

3.  Chlorate;  Perchlorate 80 

4.  Potassa 81 

5.  Ferric  oxide;  Alumina 81 

6.  Lime 81 

Gas-  and  Ammonia  manufacture 82 

Illuminating-gas 82 

Gas-purifying  compound 84 

Gas  liquor 85 

Ammonia 86 

Ammonium  sulphate ..,....,..,.......,., ,..-..  87 


VI  TABLE  OF  CONTENTS. 

PAGE 

Addendum:  Calcium  carbide 87 

Coal-tar  Industry 87 

Tar 87 

Commercial  benzol 88 

Differentiation  of  coal-tar  benzol  from  petroleum,  benzin, 

brown-coal  oils,  etc 90 

Naphtalin ;  Anthracene 90 

Carbolic  acid 91 

Crude  carbolic  acid  and  Carbolic-acid  preparations 92 

Coal-tar  pitch 92 

Mineral  Oils 93 

Petroleum ;  Benzin 93 

Kerosene 94 

Lubricating  oils 95 

Oils  and  Fats 97 

Soaps 100 

Glycerin 102 

Sugar 102 

Alcohol  Manufacture  (Brandy,  etc.) 107 

Starch 107 

Malt 108 

Mash 109 

Alcoholometry 110 

Fusel-oil,  etc Ill 

Vinegar 113 

Wine 115 

Beer  Brewing 116 

Tanning  Materials 119 

Dyeing 121 


LITERATURE. 


LUNGE,  Chemisch-Technische  Untersuchungsmethoden.  3  vol- 
umes. Berlin,  1899-1900. 

LUNGE,  Taschenbuch  fur  die  /Soda-,  Pottasche-  und  Ammoniak- 
fabriMtion.  3d  edit.  Berlin,  1900. 

AHRENS,  Arileitung  zur  chemisch-technischen  Analyse.  Stutt- 
gart, 1901. 

TREADWELL,  Kurzes  Lehrbueh  der  analytischen  Chemie.  2d 
edit.  Leipzig,  1902-1903. 

A.  CLASSEN,  Ausgewahlte  MetTioden  der  analytischen  Chemie. 
2  volumes.  Braunschweig,  1901-1903. 

KONIG,  Untersuchung  landwirtschaftlich  und  gewerblich  wich- 
tiger  Stoffe.  Berlin,  1891. 

KO'NIG,  Chemische  Zusammensetzung  der  menschlichen  Nah- 
rungs-  und  G-enussmittel.  4th  edit,  by  BOmer.  Berlin, 
1903. 

WINKLER,  Lehrluch  der  technischen  Gasanalyse.  3d  edit. 
Leipzig,  1901. 

HEMPEL,  Gasanalytische  Methoden.  3d  edit.  Braunschweig, 
1900. 

NEUMANN,  Gasanalyse  und  Gasvolumetrie.    Leipzig,  1901. 

WALTER  und  GARTNER,  Untersuchung  und  Beurteilung  der 
Wasser.  4th  edit.  Braunschweig,  1895. 

BENEDIKT,  Analyse  der  Fette  und  Wachsarten.  4th  edit,  by  F. 
Ulzer.  Berlin,  1903. 

GNEHM,  Taschenbuch  fur  Fdrberei  und  Farbenfdbrikation. 
Berlin,  1902, 


TECHNO-CHEMICAL  ANALYSIS. 


GENERAL  PART. 


I—SCOPE  OF  TECHNO-CHEMICAL  ANALYSIS. 

TECHNO-CHEMICAL  ANALYSIS  comprises: 

1.  The   examination   of  raw  material  for   chemical 
factories  and  other  technical  industries  in  which  the 
chemical  nature  of  the  substances  plays  an  important 
role. 

2.  The   operative   control    of    chemical  factories  by 
chemical  and  physical  means. 

3.  The  examination  of  the  end-products  respecting 
the  properties  which  have  an  important  bearing  on 
their  employment,  and  which  are  hence  to  be  guaran- 
teed to  the  purchaser. 

All  these  investigations  may  be  of  the  most  varied 
character.  Frequently  only  qualitative  tests  are  made 
as  to  whether  certain  injurious  impurities  are  absent, 
or  whether  color,  luster,  density,  or  solidity  of  the  end- 
product  meet  the  requirements  demanded.  Very  often; 


2  TECHNO-CHEMJCAL  ANALYSIS. 

however,  quantitative  determinations  are  required,  it 
may  be  of  the  valuable  chief  constituent,  or  of  useful 
or  injurious  secondary  constituents;  or  it  may  be  of 
the  action  exerted  by  the  product  (e.g.,  the  viscosity 
of  lubricating-oils,  or  the  colorific  power  of  dyes).  In 
many  cases  empirical  methods,  useful  for  practical  pur- 
poses, are  employed;  very  often,  however,  the  methods 
employed  in  scientific  chemical  analysis  must  be 
adopted,  and  with  every  attention  to  extreme  accu- 
racy. 


II.— GENERAL  OPERATIONS  PRECEDING 
THE  ANALYSIS. 

The  preparation  of  a  uniform  sample  is  of  the  utmost 
importance.  If  this  has  not  been  properly  effected, 
the  techno-chemical  analysis  is  utterly  worthless,  and 
it  may  lead  the  investigator  altogether  astray.  In  the 
case  of  finely  pulverulent  substances  the  preparation 
of  a  sample  presents  no  great  difficulties;  with  fluids  and 
gases  the  object  is  also  easily  attained,  but  in  all  these 
cases  certain  rules  of  procedure  must  be  followed  in 
order  to  obtain  a  correct  average  sample.  Where, 
however,  the  material  occurs  in  the  form  of  coarse 
lumps,  the  preparation  is  attended  by  particular  diffi- 
culties. Of  such  substances  large  quantities  must  be 
taken,  the  lumps  comminuted,  again  thoroughly  mixed, 
and  the  sample  finally  taken  from  the  mixture, 
and,  inclosed  in  sealed  bottles,  handed  over  to  the 
chemist. 

Solids  must  then  be  further  comminuted  in  the  labora- 
tory, until  they  are  reduced  to  a  sufficiently  fine  powder 
to  be  available  for  analysis.  In  doing  this,  special  pre- 
cautions must  frequently  be  observed  in  order  to  avoid 
loss  of  moisture,  or  to  prevent  any  attraction  of  mois- 
ture, oxygen,  carbonic  acid,  etc.,  from  the  atmosphere. 

3 


4  TECHNO-CHEMICAL  ANALYSIS. 

Reduction  to  a  coarse  powder  is  usually  effected  in  an 
iron  mortar,  while  porcelain,  agate,  or  steel  mortars  are 
employed  for  preparing  very  fine  powders. 

This  procedure  is  of  course  unnecessary  in  the  case 
of  fluids  and  gases;  nevertheless,  even  with  these,  cer- 
tain precautions  must  be  taken  to  assure  thorough 
mixing,  and  in  any  event  the  temperature  of  the  sample 
must  be  taken,  and  allowance  made  for  it. 

In  the  analysis,  solids,  and  frequently  liquids  also, 
are  weighed;  the  latter  are,  however,  also  often  meas- 
ured, but  gases  are  in  all  cases  measured. 

For  weighing  off,  both  coarse  and  fine  balances  must 
be  employed.  Analytical  balances  which  turn  with 
0.1  mgrm.  (or  after  long-continued  use  often  only  with 
0.2  mgrm.)  are  used  only  when  the  scientific  chemical 
methods  of  analysis  are  employed,  and  where  the  quan- 
tity of  the  sample  taken  for  the  analysis  does  not  ex- 
ceed 1  or  at  most  2  grm.  In  cases  where  larger  quan- 
tities are  weighed  off,  as  is  frequently  done  when  it  is 
required  to  dissolve  the  sample  in  order  to  take  only  a 
portion  for  analysis,  the  sufficiently  sensitive  hand-  or 
tare-balance  is  to  be  preferred,  as  the  weighing  is  much 
more  rapidly  done.  Under  all  circumstances,  how- 
ever, the  sensitiveness  of  the  balance  and  the  accuracy 
of  the  weighing  must  be  decidedly  greater  than  the 
limit  of  error  for  the  individual  case,  and  which  repre- 
sents the  sum  of  all  unavoidable  errors  incident  to  both 
the  method  and  the  manipulation. 

In  technical  analyses,  such  a  quantity  is  frequently 
weighed  off  that,  by  titration,  the  volume  of  reagent 


OPERATIONS  PRECEDING  THE  ANALYSIS.          5 

used  up  gives  directly,  and  without  any  calculation, 
the  percentage  of  constituent  sought,  by  a  simple 
reading-off. 

Fluids,  too,  are  at  times  weighed  off  in  technical 
analyses,  those  that  are  non-volatile  and  unchanged  on 
exposure  to  air  being  weighed  in  suitable  vessels,  and 
others  in  glass  bottles  provided  with  glass  stoppers,  or 
in  pipettes  provided  with  a  stopcock.  Usually,  how- 
ever, fluids  are  measured,  in  which  case  the  tempera- 
ture must  always  be  noted,  and  the  specific  gravity 
taken. 

Gases  are  frequently  examined  at  the  place  of  col- 
lection, in  which  case  the  apparatus  employed  in  the 
analysis  serves  for  both  drawing  off  and  measuring  the 
sample  of  gas.  In  doing  this,  however,  care  must  be 
exercised  to  take  the  sample  of  gas  at  the  proper  place 
or  point,  avoiding  also  the  introduction  of  any  impuri- 
ties, such  as  soot,  or  even  admixture  of  atmospheric 
air.  The  former  may  be  excluded  by  employing  a 
filter  of  cotton  or  asbestos  within  the  inlet-tube;  the 
latter,  by  passing  the  inlet-tube  through  a  perforated 
stopper  which  closely  fits  the  hole  in  the  gas-pipe  or 
chimney  from  which  the  gas  is  to  be  taken. 

In  other  cases  the  samples  of  gas  must  be  taken  to 
be  subjected  to  analysis  elsewhere.  The  samples  are 
best  collected  by  drawing  the  gas  into  glass  tubes  both 
ends  of  which  are  drawn  out,  and  of  which  several  may 
be  successively  introduced  and  filled;  the  tubes  are 
best  closed  by  fusion,  rubber  caps  being  not  so  good. 
In  many  cases  the  transportation  of  the  samples  is 


6  TECHNO-CHEM1CAL  ANALYSIS. 

satisfactorily  accomplished  in  glass  bottles,  zinc  ves- 
sels, etc.  Rubber  vessels  are  very  convenient  to  use,  as 
it  is  only  necessary  to  press  them  together,  when  the 
gas  readily  fills  them  on  releasing  the  pressure.  Fre- 
quently, however,  the  gas  may  be  rendered  impure 
thereby,  or  a  diffusion  of  the  gas  through  the  rubber 
walls  is  to  be  feared. 


III.  TECHNICAL  GAS  ANALYSIS. 

In  many  cases,  in  the  illuminating-gas  industry,  the 
technical  chemist  must  employ  the  methods  of  scientific 
gas  analysis,  in  which  mercury  is  employed  as  the  con- 
fining liquid.  In  the  majority  of  cases,  however,  the 
methods  and  apparatus  employed  in  technical  analysis 
are  used,  in  which  water  and  aqueous  fluids  serve  as  the 
confining  liquid,  and  which  enable  the  operations  to  be 
much  more  simply  and  rapidly  performed. 

In  technical  gas  analysis,  the  object  must  be  to  oper- 
ate so  rapidly  that  variations  of  the  barometer  during 
the  operation  may  be  disregarded.  Those  of  the  ther- 
mometer are  avoided,  where  it  can  be  done,  by  placing 
the  measuring-tube  within  a  water-mantle;  otherwise  a 
certain  time  must  be  allowed  to  elapse  before  each  read- 
ing-off,  and  until  the  temperature  has  become  station- 
ary. By  this  procedure  it  becomes  unnecessary  to  re- 
duce the  volume  of  gas  to  normal  (0°  C.  and  760  mm. 
pressure). 

We  will  here  mention  only  the  more  important  appa- 
ratus employed  in  technical  analysis. 

1.  Cl.  Winkler's  gas-burette  (fig.  1)  consists  of  two 
limbs,  A  and  B,  connected  by  means  of  a  rubber  tube,  C, 
to  form  a  U-tube.  A  is  a  measuring-tube  graduated  in 

7 


8 


TECHNO-CHEMICAL  ANALYSIS. 


100  cc.  It  is  closed  above  and  below  by  glass  cocks. 
The  upper,  a,  is  simple;  the  lower,  6,  is  a  three-way 
cock,  having,  besides  the  usual  transverse  perforation, 
also  a  longitudinal  one,  so  that 
communication  can  be  estab- 
lished with  the  air  by  turning 
the  cock.  The  second  limb,  B, 
is  not  graduated,  and  bears  a 
side  tube  near  the  bottom  pro- 
vided with  a  cock,  c.  The  whole 
may  be  brought  to  a  perpendic- 
ular or  any  inclination  desired 
by  being  fixed  in  a  stand.  The 
gas  to  be  examined  is  allowed  to 
enter  at  6,  and  passes  out  at  a, 
or  vice  versa,  until  the  tube  A  is 
filled  with  the  pure  gas.  a  and 
b  are  then  closed,  the  confining 
liquid  then  introduced  into  B, 
until  it  begins  to  flow  out  from 
the  longitudinal  perforation  in  6, 
and  the  cock  b  so  turned  that  A 
and  B  are  connected,  i.e.,  the 
liquid  may  pass  from  B  to  A,  and  act  upon  the  gas.  By 
inclining  the  apparatus  to  and  fro,  the  absorption  is  pro- 
moted, until  it  is  complete.  The  tubes  A  and  B  are  then 
manipulated  so  that  the  level  of  the  liquid  in  both  tubes 
is  at  the  same  height,  by  allowing  liquid  to  flow  out 
from  c  or  C,  after  which  the  volume  of  the  gas  remaining 
in  A  is  read  off. 


FIG.  1. 


TECHNICAL  GAS  ANALYSIS. 


9 


Winkler's  burette  is  particularly  well  adapted  for  such 
cases  where  but  one  constituent  of  a  gas  is  to  be  deter- 
mined; e.g.,  carbonic  acid  in  smoke-gases,  saturation- 
gases,  lime-oven  gases,  etc.  In 
such  a  case  the  same  absorption 
liquid  is  used;  in  the  case  before 
us  it  is  soda-lye. 

2.  Bunte's  burette  (fig.  2) 
consists  of  a  measuring-tube,  A, 
closed  above  and  below  by  cocks, 
a  and  6.  a  is  a  three-way  cock. 
Above  the  latter  is  a  funnel,  t, 
which  bears  a  scratch  or  mark 
at  about  its  center.  The  tube 
A  has  a  capacity  of  a  little  over 
110  cc.,  and  is  graduated  from 
above  downwards,  from  100  to  0, 
the  graduations  being  then  con- 
tinued 10  divisions  further.  The 
tube  A  is  loosely  suspended  in  a 
stand,  which  at  the  same  time 
supports  a  bottle  or  funnel,  B, 
which  is  connected  with  the  tip 
of  the  burette,  c,  by  means  of  a 
rubber  tube.  A  second  bottle, 
C,  is  also  required,  it  being  ar-  FIG.  2. 

ranged  so  that  liquid  may  be  drawn  or  forced  from  or 
into  A. 

The  bottle  B  is  then  connected  with  c,  and  water  poured 
into  it  until  the  liquid  has  entered  the  funnel,  t'}  the  cocks 


10  TECHNO-CHEMICAL  ANALYSIS, 

are  then  closed  and  the  rubber  tube  removed  from  c. 
The  longitudinal  perforation  of  a  is  then  made  a  part 
of  the  passage  through  which  the  gas  to  be  examined  is 
to  be  drawn,  and  b  opened,  when  the  gas  will  enter  into 
A.  After  waiting  a  short  time  until  the  water  in  A  has 
fallen  about  5  cc.  below  the  zero-mark,  close  a,  and  by 
means  of  the  bottle  B  force  water  into  A,  until  the 
level  is  about  5  cc.  above  the  zero-mark,  so  that  the 
gas  is  somewhat  compressed,  remove  B  again,  and  by 
cautiously  opening  a,  allow  water  to  flow  out  until  the 
liquid  stands  at  the  zero-mark,  and  then  pour  water 
into  t  up  to  the  mark  or  scratch.  The  gas  will  now  be 
under  the  atmospheric  pressure,  together  with  that 
exerted  by  the  small  column  of  water  in  t]  and  under 
this  pressure  all  subsequent  measurements  must  be 
made. 

In  order  to  next  introduce  an  absorbing  fluid  into  the 
burette,  unite  the  tip  of  c  with  the  bottle  C,  draw  off 
the  water  from  A  so  far  as  possible,  close  b}  immerse  c 
in  a  dish  containing  the  liquid  used  for  absorbing,  and 
again  open  b.  A  certain  quantity  of  the  liquid  will  now 
enter  A.  Then  close  b,  remove  A  from  the  stand,  shake 
it  well,  replace  it  in  the  stand,  immerse  c  in  the  dish 
of  absorbing  fluid,  and  open  b.  A  further  quantity  of 
the  fluid  will  now  enter  A;  and  these  operations  are 
repeated  until  no  more  liquid  is  drawn  in,  i.e.,  no  more 
gas  is  absorbed.  The  proper  pressure  is  then  brought 
about  as  above,  by  pouring  water  into  t,  opening  a,  and 
allowing  the  water  to  run  into  A  from  t,  whereby  the 
walls  of  A  are  rinsed  down,  and  the  absorbing  liquid 


TECHNICAL  GAS   ANALYSIS.  11 

becomes  covered  with  a  layer  of  pure  water.  Care  must 
be  taken  that  on  opening  a,  the  water  in  t  is  on  a  level 
with  the  mark ;  the  volume  is  then  read  off  in  A.  The 
volume  of  gas  that  has  disappeared  corresponds  to  the 
absorbed  gaseous  constituent. 

Other  constituents  of  gases  may  be  determined  in  a 
similar  manner,  as  an  example  will  best  show;  e.g.,  in 
a  mixture  of  carbonic  acid,  carbonic  oxide,  and  nitrogen, 
such  as  occurs  in  generator  gases.  The  carbonic  acid 
is  always  first  absorbed  by  potassa  lye;  the  original 
volume  of  gas  is  thereby  reduced  from  100  down  to  90, 
according  to  which  the  gas  contains  10  per  cent,  by 
volume  of  C02.  A  now  contains  potassa  lye.  It  is  not 
necessary  to  remove  the  lye  entirely,  as  the  absorption 
of  oxygen  must  next  be  accomplished  by  pyrogallol  in 
an  alkaline  solution.  For  this  purpose,  only  about  half 
of  the  potassa  lye  is  drawn  off  from  A  a  b,  and  t  is  im- 
mersed in  a  dish  containing  aqueous  pyrogallol  solution, 
of  which  some  is  then  made  to  enter  A.  By  manipulat- 
ing as  already  described,  we  find  the  volume  of  gas 
reduced  from  90  to  85,  and  thus  ascertain  the  gas  to 
contain  5  per  cent,  of  oxygen.  We  now  come  to  the 
carbonic  oxide.  This  must  be  absorbed  by  an  ammo- 
niacal  solution  of  cuprous  chloride,  which  is  entirely 
incompatible  with  the  alkaline  pyrogallol  solution  re- 
maining in  A.  The  pyrogallol  solution  is  therefore 
drawn  off  as  completely  as  possible  by  aid  of  the  bottle 
C,  water  allowed  to  enter  A  through  t  and  a,  then  again 
drawn  off,  and  this  procedure  repeated,  whereby  A  is 
cleansed.  The  new  absorbing  fluid  is  now  introduced, 


12  TECHNO-CHEMICAL  ANALYSIS. 

and  the  residual  gas  energetically  acted  upon  with  the 
cuprous-chloride  solution  until  all  the  CO  is  absorbed, 
which  is  more  difficult  to  accomplish  and  requires  more 
time  than  is  the  case  with  C02  and  0.  The  error  in 
reading-off  caused  by  the  ammoniacal  pressure  is  reduced 
to  a  minimum  by  finally  allowing  water  to  run  from  t 
into  A  to  form  a  layer  on  the  liquid  therein.  We  now 
find  the  volume  of  gas  to  be,  for  instance,  65;  we  hence 
infer  that  20  per  cent,  of  CO  was  present  in  the  gas. 
The  remainder,  65  per  cent.,  consists  chiefly  of  nitrogen. 
It  might  also  contain  hydrogen,  methane,  and  other  non- 
absorbable  gases,  but  in  the  case  here  instanced  these 
are  present  only  in  very  small  quantities.  Where  these 
gases  are  present  in  large  quantities,  and  they  must  be 
determined,  the  object  may  be  accomplished  by  pass- 
ing the  gasc  through  a  Drehschmidt  platinum  tube  (see 
below)  into  another  burette  (Bunte's),  the  operation 
being  conducted  as  described  below. 

Bunte's  burette  is  particularly  well  adapted  for  those 
cases  in  which  a  transportable  apparatus  is  required, 
and  in  which  but  few  of  the  gaseous  constituents  are  to 
be  separated  by  absorption  fluids.  It  is,  however, 
also  adapted  for  use  in  complicated  cases,  as  above 
described,  but  then  the  advantage  offered  by  its  ready 
transportability  is  minimized. 

3.  Orsat's  apparatus  (fig.  3).  In  its  usual  form  this 
consists  of  a  gas-burette,  A,  inclosed  within  a  water- 
mantle,  and  connected  by  means  of  a  rubber  tube 
with  a  leveling-bottle,  E,  and  with  the  capillary 
tube,  a,  The  tube  a  bears  three  cocks;  at  right 


TECHNICAL  GAS  ANALYSIS. 


13 


FIG.  3. 


angles,  and  directed  downwards,  and  which  are  con- 
nected with  the  U-shaped  receiv- 
ers, B,  C,  and  D;  it  also  is  provided 
with  the  three-way  cock,  e.  The 
whole  apparatus  is  inclosed  within 
an  easily  transportable  case.  As  a 
rule,  the  upper  part  of  the  burette 
is  made  wider,  and  is  ungraduatedj 
the  lower,  narrower  part  is  gradu- 
ated in  cubic  centimeters  from  60 
to  100,  the  zero-point  being  at  the 
upper  part  of  the  tube.  To  better 
insure  a  good  surface  contact  be- 
tween the  gas  and  the  liquid  in  the  receivers  B,  C,  and  D, 
bundles  of  glass  tubes  are  placed  in  the  latter.  The  first 
receiver,  B,  is  always  filled  with  potassa  lye  for  the  absorp- 
tion of  carbonic  acid ;  the  second  one,  C,  with  an  alkaline 
pyrogallol  solution,  or  even  a  small  stick  of  phosphorus, 
immersed  in  water,  to  absorb  the  oxygen.*  The  third 
receiver,  C,  is  filled  with  ammoniacal  cuprous-chloride 
solution  and  pieces  of  copper  wire,  to  absorb  carbonic 
oxide.  In  a  mixture  of  gases,  therefore,  C02,  0,  and 
CO  may  be  determined  directly,  and  the  N  by  differ- 
ence. Special  devices  have  also  been  devised  in  order 
to  permit  other  gases,  for  instance  heavy  hydrocar- 


*  It  is  much  more  convenient  to  use  phosphorus  than  pyrogallol, 
because  the  latter  can  be  used  but  a  few  times,  whereas  phos- 
phorus can  be  used  for  hundreds  of  analyses.  Phosphorus  can  not, 
however,  be  used  where  the  vapors  of  heavy  hydrocarbons  are  pres- 
ent, and  at  temperatures  below  16°  C. 


14  TECHNO-CHEMICAL  ANALYSIS. 

bons,  hydrogen,  methane,  etc.,  to  be  determined  at 
the  same  time.  These  devices,  however,  make  the 
apparatus  so  complicated  that  its  great  advantages, 
simplicity  of  use  and  ready  transportability,  are  lost. 
The  only  modification  that  has  been  retained  is  that  of 
Lunge.  This  is  for  the  determination  of  hydrogen,  and 
it  requires  the  addition  of  a  wide  receiver,  a  platinum- 
asbestos  tube,  and  a  lamp;  this  makes  the  apparatus 
about  one-third  larger  than  otherwise. 

To  use  the  apparatus,  the  gas  is  drawn  into  the 
burette,  after  the  latter  has  been  filled  with  water  to 
the  upper  mark  by  raising  the  bottle  E  to  a  sufficient 
height,  the  three-way  cock  being  connected  with  the 
source  of  gas  supply,  and  so  set  as  to  communicate 
with  the  capillary  tube,  E  being  then  lowered.  E  is 
next  raised  until  the  water  in  it  and  in  A  stands  at 
the  same  level  at  100.,  whereupon  e  is  closed.  The 
liquids  in  B,  C,  and  D  must  previously  have  been  intro- 
duced and,  by  means  of  the  leveling-bottles  and  the 
space  a,  brought  to  marks  just  below  the  cocks  b,  c,  and 
d.  b  is  now  opened,  and  the  gas  forced  from  A  into  B 
by  lifting  the  bottle  E,  whereby  the  gas  comes  into 
contact  with  the  potassa  adhering  to  the  glass  "tubes, 
and  the  carbonic  acid  is  rapidly  absorbed.  After  two 
or  three  minutes  draw  the  gas  back  into  A  again  by 
lowering  E,  when  the  potassa  solution  will  flow  back 
and  again  fill  B  up  to  the  mark,  whereupon  the  cock 
must  at  once  be  closed.  Now  bring  the  water  in  A  and 
E  to  the  same  level  by  raising  E  to  a  suitable  height, 
and  read  off  the  volume  of  gas  in  a  6;  the  gas  that  has 


TECHNICAL  GAS  ANALYSIS.  15 

disappeared  corresponds  to  the  carbonic-acid  content. 
In  the  same  manner  force  the  gas  into  C,  whereby  the 
oxygen  is  absorbed  by  the  pyrogallol-potassium  solu- 
tion or  phosphorus.  This  requires  a  somewhat  longer 
time  than  is  the  case  with  carbonic  acid,  and  it  must  be 
facilitated  by  repeatedly  forcing  the  gas  into  and  out 
of  the  tube  C.  The  absorption  of  the  carbonic  oxide 
in  D  is  still  more  slow ;  furthermore  the  cuprous-chloride 
solution  can  only  be  used  three  or  four  times,  and  must 
then  be  renewed. 

In  all  these  cases  the  space  within  the  capillary  must 
be  regarded  as  having  an  injurious  effect  on  the  reading- 
off,  and  on  this  account  alone  the  analysis  can  not  be 
accurate.  To  this  must  also  be  added  the  solubility 
of  the  carbonic  acid  in  the  water  used  as  the  confining 
liquid,  and  which  must  be  allowed  for,  of  course,  in 
other  apparatus  also.  Very  accurate  determinations 
can  not  be  made  with  the  Orsat  apparatus;  the  latter  is, 
however,  excellently  adapted  for  use  in  the  factory,  be- 
cause of  the  ease  and  rapidity  with  which  the  manipu- 
lations may  be  carried  out,  and  because  of  its  transpor- 
tability, etc. 

4.  HempePs  gas-burette  (fig.  4),  because  of  its  size, 
is  not  readily  available  for  use  otherwise  than  in  the 
laboratory,  but,  on  the  other  hand,  it  is  adapted  for 
the  most  varied  uses,  so  that  with  it  most  of  the  prob- 
lems of  gas  analysis  may  be  solved  with  a  compara- 
tively high  degree  of  accuracy.  The  apparatus  con- 
sists of  the  gas-burette  or  measuring-tube,  A,  which 
is  connected  with  the  leveling-tube,  B,  and  a,  suit- 


16 


TECIINO-CHEMICAL  ANALYSIS. 


able  number  of  gas-pipettes,  C,  of  varied  form,  as 
shown  in  figures  5,  6,  and  7.  The  measuring-tube  A 
is  sometimes  inclosed  within  a  water-mantle,  which, 
however,  greatly  increases  the 
difficulty  of  manipulating,  and 
which  can  generally  be  dis- 
pensed with.  The  upper  end 
of  the  tube  forms  a  capillary, 
upon  which  is  fastened  a  piece 
of  soft-rubber  tubing  provided 
with  a  pinchcock,  a,  and  in 
which  is  then  fastened  a  twice- 
bent  capillary  tube,  i.  From 
the  pinchcock,  a,  to  a  mark  just 
above  the  wooden  foot,  the  tube 
A  holds  100  cc.,  graduated  in 
1/5-cc.  Below  the  mark,  the 
tube  is  narrowed  and  bent  at 
a  right  angle;  the  bent  part 
protrudes  from  the  side  of  the 
wooden  foot,  and  the  same  is 
the  case  with  the  simple,  non- 
graduated  leveling-tube,  B.  In 
the  case  of  mixtures  of  gases 
that  can  not  well  be  collected  over  water,  a  three- 
way  cock  is  sealed  into  the  measuring-tube  between 
the  zero-mark  and  the  foot,  and  the  tube  is  then 
filled  just  as  the  Winkler  tube  is  filled.  The  meas- 
uring-tube in  its  usual  form  is  filled  with  water  by 
elevating  the  tube  B?  until  the  water  rises  above  the 


FIG.  4. 


TECHNICAL  GAS  ANALYSIS. 


17 


pinchcock  a;  then  the  gas  is  drawn  in  by  lowering  B 
and  opening  a,  until  the  water,  when  it  is  level  in  both 
A  and  B,  stands  at  the  zero-mark  in  A. 

To  treat  the  gas  with  absorption  fluids  or  otherwise, 
it  is  drawn  into  a  gas-pipette,  C,  and  always  by  elevating 
B  and  opening  a.  The  simple  absorption  pipette 
(fig.  5)  consists  of  the  U-formed  capillary  h,  pinchcock 
I),  and  the  bulbs  c  (200  cc.)  and  d  (150  cc.).  In  order  to 
fill  the  tube,  pour  the  fluid  into  d,  and  apply  suction  at  6, 
until  c  and  b  are  filled,  while  d  remains  almost  empty, 
thus  allowing  room  for  the  return  of  liquid  into  d} 
when  gas  enters  c.  The  absorption  pipette  for  solid 
reagents  (fig.  6)  is  constructed  upon  exactly  the  same 
principle,  but  instead  of  the  bulb  c,  the  apparatus  is 
provided  with  a  vessel  e,  the  neck  at  the  lower  end  of 


FIG.  5. 


FIG.  6. 


FIG.  7. 


which  is  closed  with  a  stopper,  and  in  which  phos- 
phorus, copper  wire,  etc.,  may  be  put.  The  com- 
pound absorption  pipette  (fig.  7)  is  provided  with  a 
second  pair  of  bulbs,  /  and  g,  /  being  filled  with  water 
until  it  just  enters  g.  These  bulbs  are  employed  with 


18  TECHNO-CHEMICAL  ANALYSIS. 

reagents  which  must  be  protected  from  exposure  to 
the  air  (pyrogallol-potassium,  cuprous-chloride  solu- 
tion, etc.). 

In  fig.  4  we  see  a  U-formed  glass  capillary,  i,  which 
is  connected  with  the  measuring-tube  A  and  the  pi- 
pettes. Before  use  these  are  filled  with  water  in  order 
to  obviate  the  "  error-causing  "  space.  By  elevating  B 
and  opening  the  pinchcocks  a  and  6,  the  gas  is  forced 
from  A  into  C;  b  is  then  closed,  the  pipette  disconnected 
the  apparatus  gently  shaken  to  facilitate  the  absorp- 
tion of  the  gas,  the  pipette  again  connected  with  A, 
and  the  gas  again  drawn  into  A  by  lowering  B,  by 
which  procedure  the  absorption  liquid  once  more  fills 
the  capillary  tube  i,  but  must  not  be  allowed  to  enter 
A.  The  pinchcock  a  is  now  closed,  the  pipette  again 
removed  and  stoppered,  and  the  tube  B  elevated  until 
the  water  is  on  a  level  in  both  A  and  B;  the  volume 
of  gas  is  then  read  off. 

For  the  consecutive  absorption  of  individual  gas 
constituents  a  corresponding  number  of  pipettes  are 
required,  and  the  gas  must  be  consecutively  forced 
into  the  tubes,  and  the  contents  of  each  tube  returned 
to  A  in  order  to  be  measured.  In  this  manner,  carbonic 
acid,  for  instance,  can  first  be  absorbed  by  potassa 
lye,  then  oxygen  by  alkaline  pyrogallol  solution  or 
phosphorus,  and  next  carbonic  oxide  by  cuprous- 
chloride  solution,  as  described  on  page  14.  In  addi- 
tion, however,  heavy  hydrocarbons  may  be  absorbed 
by  fuming  sulphuric  acid;  nitric  oxide  by  potassium 
permanganate  acidulated  with  sulphuric  acid;  nitro- 


TECHNICAL  GAS  ANALYSIS.  19 

gen  dioxide  by  concentrated  sulphuric  acid;  ammonia 
by  diluted  sulphuric  acid;  chlorine,  hydrochloric  acid, 
hydrogen  sulphide,  or  sulphur  dioxide,  by  potassa  lye; 
or  the  chlorine  or  sulphur  dioxide  by  potassium-iodide 
solution.  These  reagents  must,  however,  be  used  one 
after  another  systematically,  so  that  one  gas  is  not 
prematurely  absorbed  with  one  of  the  others.  For 
instance,  in  order  to  determine  chlorine  and  carbonic 
acid  in  a  gas,  potassa  solution  must  not  be  employed  at 
the  start,  but  the  chlorine  should  first  be  absorbed  by 
potassium  iodide,  and  after  measuring  the  gas  remain- 
ing, the  carbonic  acid  then  absorbed  by  potassa.  When 
heavy  hydrocarbons  are  to  be  absorbed,  this  must  be 
done  after  the  carbonic  acid  has  been  removed,  but 
before  the  treatment  with  pyrogallol  solution  and 
cuprous  chloride. 

DETERMINATION  OF  GASES  BY  COMBUSTION. 

The  Hempel  burette  may  also  be  easily  employed 
in  those  methods  in  which  the  gases  are  determined 
by  combustion,  and  which  is  usually  the  case  with 
hydrogen  and  methane.  In  employing  it  thus,  how- 
ever, all  the  gaseous  constituents  removable  by  absorp- 
tion fluids  must  first  be  removed;  to  the  residual  gas, 
after  its  volume  has  been  measured,  a  measured  quantity 
of  atmospheric  air,  or  even  oxygen,  if  necessary,  suffi- 
cient for  combustion,  is  added.  Usually  a  preliminary 
experiment  is  made  in  order  to  approximately  determine 
the  quantity  of  air  required  for  the  combustion,  if 
no  data  are  at  hand  that  render  the  experiment  un- 


20  TECHNO-CHEMICAL  ANALYSIS. 

necessary.  During  the  combustion,  1  volume  of  02 
disappears  for  every  2  volumes  of  H2;  hence  if  only 
hydrogen  is  present,  two-thirds  of  the  volume-con- 
traction after  the  combustion  may  be  calculated  as 
hydrogen.  In  the  case  of  methane,  1  volume  of  CH4 
always  requires  2  volumes  of  02,  with  the  formation 
of  1  volume  of  C02,  besides  2H20,  in  liquid  form; 
hence  a  contraction  of  2  volumes.  The  volume  of 
methane  thus  corresponds  to  one-half  the  observed 
contraction.  If  now  the  C02  is  absorbed  by  potassa 
lye,  the  original  volume  of  methane  exactly  corresponds 
to  the  contraction  thus  caused,  or  but  one-third  of  the 
total  contraction. 

When  both  hydrogen  and  methane  are  present,  and 
we  measure  the  contraction  directly  resulting  from 
the  combustion,  KI,  and  the  contraction  resulting 
from  the  absorption  of  carbonic  acid,  K2,  then  K2 
will  represent  the  volume  of  methane,  and  f(Ki-2K2) 
that  of  the  hydrogen. 

The  combustion  may  be  effected  either  by  explo- 
sion, or  by  means  of  heated  platinum  or  palladium. 
The  explosion  is  effected  by  means  of  an  electric  spark  in 
a  eudiometer  hi  which  a  piece  of  platinum  wire  is  fused, 
or  in  a  Hempel tl  explosion-pipette  "  similarly  provided. 
It  occurs,  "however,  only  when  the  gases  are  mixed  in 
certain  proportions,  and  requires  a  rather  complicated 
apparatus,  so  that  it  is  not  well  adapted  for  technical 
purposes. 

Much  more  convenient  is  the  other  method  of  com- 
bustion, in  which  even  fractional  combustion  may  be 


TECHNICAL  GAS  ANALYSIS.  21 

effected,  i.e.,  the  more  readily  combustible  hydrogen 
is  first  burned  by  the  aid  of  gently  ignited  palladium, 
and  then  the  more  difficultly  combustible  methane, 
by  means  of  strongly  ignited  palladium  or  platinum 
wire. 

For  the  combustion  of  the  hydrogen  alone,  the 
Winkler  palladium-asbestos  capillary  is  best  adapted. 
This  has  exactly  the  same  form  as  the  capillary  tube, 
i,  shown  in  fig.  4,  and,  like  it,  is  interposed  between 
the  burette  tip  a,  and  a  pipette,  C.  In  its  horizontal 
part  is  placed  a  thread  of  palladium-asbestos,  which 
is  prepared  by  impregnating  long-fibered  asbestos  with 
a  concentrated  mixture  of  solutions  of  palladious 
chloride,  sodium  formate,  and  sodium  carbonate,  and 
then  drying  at  a  gentle  heat.  The  threads  are  intro- 
duced Into  a  glass  capillary  tube,  16  to  18  cm.  long, 
and  1  mm.  bore  (6  mm.  external  diameter),  which  is 
then  bent  at  a  right  angle  3J  to  4  cm.  from  each  end. 
During  the  operation  the  capillary  is  heated  by  a  small 
gas-  or  alcohol-flame,  but  never  to  a  point  sufficient 
to  soften  it. 

After  the  residual  gas  in  the  burette  A  has  been 
measured,  the  rest  of  the  space  in  the  burette,  provided 
there  is  sufficient,  is  filled  up  to  nearly  100  cc.  with  air, 
and  another  reading  taken.  If  the  volume  of  the  resid- 
ual gas  is  too  great,  because  of  too  large  a  nitrogen  con- 
tent for  instance,  to  permit  a  sufficient  quantity  of 
air  to  be  added,  the  residual  gas  is  first  measured,  and 
then  a  quantity  of  it  is  expelled  into  the  air,  the 
remainder  measured,  and  then  a  sufficient  volume  of 


22  TECHNO-CHEMICAL  ANALYSIS. 

air  introduced  to  afford  enough  oxygen  for  combustion. 
Of  course  the  analytical  calculations  must  be  made 
accordingly.  The  mixture  is  then  slowly  forced,  by 
elevating  the  tube  B,  through  the  heated  palladium 
capillary,  and  equally  as  slowly  back  again,  great  care 
being  taken  that  not  the  slightest  drop  of  water  enters 
the  capillary,  otherwise  it  will  burst.  After  repeating 
the  passage  and  re-passage  of  the  gas  through  the 
capillary,  the  gas  is  again  measured;  two-thirds  of  the 
contraction  observed  corresponds  to  the  hydrogen  that 
was  present. 

Carbonic  oxide  is  burned  in  a  similar  manner,  but 
much  more  slowly;  and,  at  a  higher  temperature,  also 
the  heavy  hydrocarbons  which,  however,  should  have 
been  previously  absorbed  (see  page  18).  Methane  is 
not  burned  under  these  conditions. 

In  order  to  burn  methane,  the  gas  must  be  well  mixed 
with  sufficient  air,  and  brought  into  intimate  contact 
with  strongly  ignited  platinum.  For  this  purpose  plati- 
num wire  may  be  employed  which  is  electrically  heated 
within  a  small  glass  vessel  through  which  the  gaseous 
mixture  is  slowly  passed.  It  is  more  convenient  to  use 
the  Drehschmidt  platinum  capillary,  a  platinum  tube 
200  mm.  long  and  0.7  mm.  in  diameter  and  almost 
filled  with  3  or  4  platinum  wires;  to  each  end  of  the 
tube  brass  or  copper  tubes  are  soldered.  100  mm. 
of  its  length  are  heated  to  a  bright-red  heat  by  a 
gas-burner  with  a  fan-shaped  opening.  After  twice 
passing  and  re-passing  the  gas  through  the  tube  at  a 
moderately  rapid  speed,  all  the  methane  is  burned. 


TECHNICAL  GAS  ANALYSIS.  23 

The  apparatus  is  then  allowed  to  cool  off,  the  carbonic 
acid  formed  is  absorbed  by  potassa  lye,  and  the  volume 
of  the  methane  that  was  present  ascertained  by  dividing 
the  total  contraction  by  3. 

In  a  similar  manner  nitr.ous  oxide  and  nitric  oxide  may 
also  be  determined  by  combustion  with  hydrogen.  In 
the  case  of  nitrous  oxide  the  reaction  is  as  follows: 
N20+H2  =  NH+H20;  hence  the  resulting  contraction 
is  the  exact  equivalent  of  the  nitrous  oxide.  With 
nitric  oxide,  the  reaction  is  as  follows :  2NO  -f  2H2  = 
N2+2H20;  thus  the  volume  of  the  nitric  oxide  is 
equal  to  two-thirds  of  the  resulting  contraction. 

REICH'S  METHOD  OF  TITRIMETRICALLY  DETERMINING 
ABSORBABLE  GASES  (Fio.  8). 

In  this  a  definite  volume  of  the  absorption  fluid  is 
introduced  through  the  middle  tubulure  of  a  three- 
cneked  bottle,  A;  the  other  two  tubulures  serve  as  the 
inlet  and  exit,  respectively,  for  the  gases.  The  inlet 
tube,  a,  extends  to  the  bottom  of  the  bottle;  its  end 
is  best  sealed,  and  provided  with  a  number  of  small 
holes  just  above  the  tip  to  better  distribute  the  gas. 
The  exit-tube  b  ends  just  below  the  stopper,  and  is 
connected  with  the  bottle,  B,  which  serves  as  an  aspi- 
rator, the  siphon-tube  of  which  is  provided  with  a 
pinch-cock,  and  leads  into  the  measuring-cylinder  C. 

After  the  absorption  fluid,  with  a  little  of  an  indi- 
cator added,  has  been  introduced  into  A,  open  c  and 
slowly  draw  the  gas,  by  applying  suction,  through  a 
into  A,  and  then  out  through  b  and  C,  while  A  is  con- 


24 


TECHNO-CHEM1CAL  ANALYSIS. 


stantly  shaken  in  order  to  facilitate  the  reaction.  The 
moment  the  color-change  in  A  shows  that  the  liquid 
in  A  has  been  saturated,  close  c.  The  liquid  that  has 
run  out  is  measured  in  C,  and  shows  the  volume  of 


FIG.  8. 

gas  that  has  passed,  to  which  must  be  added  the  volume 
of  the  constituent  to  be  determined,  and  corresponding 
to  that  of  the  absorption  fluid  employed.  This  volume 
is  in  all  cases  the  same,  whereas  the  total  volume  natu- 
rally always  differs.  The  percentage  content  of  the 
gas  constituent  is  therefore  ascertained  by  multiplying 


TECHNICAL  GAS  ANALYSIS.  25 

the  fixed  volume  of  the  gas  constituent  by  100,  and 
dividing  the  product  by  the  total  gas  volume,  found  as 
above,  and  as  we  will  show  by  an  example.  For  more 
accurate  determinations,  the  gas  volume  ascertained 
from  the  water  that  has  run  off  from  the  aspirator 
must  be  reduced  to  0°  C.  and  760  mm.,  because  the 
volume  of  the  gas  sought  is  always  calculated  in  this 
condition;  however,  in  the  ordinary  factory  analyses 
this  is  usually  omitted  as  being  unimportant. 

Reich  had  devised  his  method  for  a  particular  case, 
which  will  be  described  below;  namely,  for  the  deter- 
mination of  sulphur  dioxide  in  the  calcination  gases 
from  pyrites,  and  for  like  cases.  This  method  is  based 
upon  the  following  reaction:  S02+2I  +2H20  =  H2S04 
+2HI.  The  determination  is  made  by  passing  the 
current  of  gas  through  a  known  volume  of  standardized 
iodine  solution  until  all  the  iodine  is  converted  into 
hydriodic  acid,  the  end-point  being  recognized  by  the 
decolorization  of  the  solution;  for  every  2  atoms  I, 
1  molecule  of  SO 2  will  be  indicated  as  having  passed 
through  the  apparatus.  To  carry  out  the  process, 
introduce  about  500  cc.  of  water  into  A,  then  add  a 
little  starch  solution  and  25  cc.  of  iodine  solution, 
which  is  best  so  prepared  that  1  cc.  of  the  solution 
exactly  corresponds  to  1  cc.  SO 2,  wherefore  the  solu- 
tion must  contain  11.3353  grm.  I  per  liter.  The  cal- 
cination gas  is  then  passed  through  the  solution  as 
above  detailed,  and  while  agitating,  until  the  liquid 
has  but  a  faint  bluish  color;  the  liquid  that  has  run 
off  from  the  aspirator  is  then  measured.  Let  us  sup- 


26  TECHNO-CHEMICAL  ANALYSIS. 

i 
pose  that  its  volume  was  320  cc.    According  to  the 

100X25 
equation  3~Q    ~-=7.25,  the   calcination  gas  contains 

7.25  volume-per  cent,  of  S02,  the  reduction  of  the  320  cc. 
to  0°  C.  and  760  mm.  being  neglected. 

Lunge  has  further  extended  this  method  to  the 
determination  of  the  total  acids  in  calcination  gases, 
e.g.,  S02,  S03,  and  HC1.  In  such  a  case  soda-lye  is 
used  as  the  absorbing  liquid,  and  phenolphtalein  as 
indicator;  the  red  color  disappears  when  for  1  equiva- 
lent of  the  acids  1  equivalent  of  NaOH  is  used  up.  In 
other  respects  the  process  is  the  same  as  above  detailed. 

Lunge  has  also  devised  an  analogous  method  for  the 
determination  of  carbonic  acid  in  the  air,  and,  in  con- 
nection with  Zeckendorf,  constructed  an  easily  trans- 
portable apparatus  for  it.  In  this  method  use  is  made 
of  the  circumstance  that  the  reddening  of  the  phenol- 
phtalein by  the  Na2C03  disappears  when  all  the 
carbonate  has  become  converted  into  bicarbonate,  as 
in  the  following  reaction:  Na2C03  +  C02  +  H20  = 
2NaHC03. 

Exceedingly  small  quantities  of  absorbable  gases  are 
determined  by  drawing  a  large  volume  of  the  gas, 
measured  by  passing  it  through  an  accurate  gas-meter, 
through  an  apparatus  affording  a  sufficiently  large 
surface  contact,  and  containing  the  absorbing  sub- 
stance in  liquid  or  solid  form,  and  afterwards,  accord- 
ing to  circumstances,  determining  the  quantity  of 
the  absorbed  gas  either  by  weighing  the  apparatus  or 
by  titrating  back. 


IV.— GAS-VOLUMETRY. 

Under  this  term  is  understood  the  operations  by 
which  the  constituent  of  a  liquid  or  solid  substance 
sought  for  is  determined  by  its  evolution  and  measure- 
ment in  the  form  of  a  gas.  The  most  important  appa- 
ratus used  for  this  purpose  are  the  following: 

1.  THE  AZOTOMETER  (FiG.  9). 

This  instrument  (Knop's)  derives  its  name  from  the 
fact  that  it  was  originally  devised  for  the  determination 
of  ammoniacal  nitrogen,  for  which  purpose  it  is  even 
at  present  mostly  used.  It  may,  nevertheless,  be  used 
in  many  other  gas-volumetric  operations.  We  will 
describe  its  original  application,  in  which  the  ammo- 
niacal nitrogen  is  liberated  in  its  elementary  form  by 
the  action  of  brominized  soda-lye  (100  grm.  caustic  soda 
dissolved  in  1}  liters  of  water,  and  adding  to  this 
solution,  while  kept  cold,  25  grm.  bromine).  A  is 
the  decomposition  vessel,  to  the  bottom  of  which  the 
small  cylinder,  a,  containing  the  brominized  lye,  is 
sealed.  A  is  placed  within  the  vessel  B,  filled  with 
water  in  order  to  maintain  the  temperature  uniform 
throughout  the  reaction.  The  cylinder,  C,  also  filled 

27 


28 


TECHNO-CHEMICAL  ANALYSIS. 


with  water,  holds  the  burette,  c,  graduated  from  above 
downwards,  the  additional  tube,  d,  and  a  thermometer, 
e.  By  means  of  the  tube  /,  sealed  in  near  the  lower 
end,  and  the  cock  g,  d  communicates  with  the  bottle  h, 
which  in  turn  is  connected  with  the  rubber  bulb,  i. 


FIG.  9. 

c  and  d  are  filled  with  water  by  pressing  i  together, 
and  then  opening  g  to  allow  water  to  run  off  until  it 
stands  at  the  zero-mark,  while  by  opening  the  cock  k, 
communication  is  established  with  the  bottle,  in  which 
the  space  surrounding  a  has  been  filled  with  the  solu- 
tion of  the  ammonium  salt,  a  itself  being  filled  with 
the  brominized  lye.  30  to  40  cc.  of  water  are  now 
allowed  to  run  out  by  opening  g,  after  which  A  is  re- 
moved from  B  and  inclined  so  that  a  little  of  the  lye 


GAS-VOLVMETRY.  29 

flows  from  a  into  the  ammonium-salt  solution,  whereupon 
the  bottle  is  shaken;  this  operation  is  repeated  until 
the  decomposition  is  complete.  A  is  then  replaced  in 
B.  and  after  waiting  about  twenty  minutes  until  the 
temperature  has  become,  uniform,  water  is  allowed 
to  flow  through-*/  until  it  stands  at  the  same  level  in  c 
and  d,  and  the  volume  then  read  off.  The  volume 
must  be  reduced  to  0°  C  and  760  mm. ;  in  such  a  case, 
however,  the  volume  must  be  increased  by  2.5  per  cent., 
in  order  to  compensate  for  the  "  absorption  of  nitrogen  " 
by  the  brominized  lye  (actually,  however,  it  is  due  to 
the  reaction  being  incomplete).  If  the  temperature  is 
not  maintained  uniformly,  i.e.,  if  the  initial  and  final 
temperatures  differ  much,  the  errors  caused  thereby 
will  be  quite  considerable.  The  reduction  is  made  by 
employing  the  following  formula,  in  which  B  represents 
the  barometric  pressure,  t  the  temperature,  and  /  the 
pressure  of  aqueous  vapor  at  the  temperature  t: 

273(B-/) 
(273  +0760 ' 

2.  THE  CALCIMETER. 

This  name  is  applied  to  apparatus  intended  for  the 
determination  of  carbonic  acid  in  carbonates,  the  acid 
being  expelled  by  means  of  strong  acids  and  deter- 
mined in  gaseous  form.  The  principle  upon  which  the 
apparatus  is  based  is  quite  similar  to  that  of  the  azo- 
tometer.  It  is  variously  constructed,  the  forms  devised 
by  Scheibler,  Dittrich,  and  Baur-Cramer  being  the 


30  TECHNO-CHEMICAL  ANALYSIS. 

ones  most  generally  used;  in  these,  water,  mercury, 
and  other  fluids  are  employed  as  confining  liquids.  All 
these,  however,  suffer  from  the  disadvantage  that  the 
liquid  wherewith  the  evolution  is  effected  retains 
some  of  the  carbonic  acid,  a  drawback  from  which  the 
apparatus  devised  by  Lunge  and  Marchlewski  is  free 
(see  Lunge's  Chem.-Techn.  Untersuchungsmethoden, 
I,  p.  142). 

3.  THE  NITROMETER  AND  GAS-VOLUMETER. 

These  apparatus,  devised  by  Lunge,  employ  mer- 
cury as  the  confining  liquid,  and  therefore  afford  more 
accurate  results  than  are  possible  with  apparatus  in 
which  water  is  used.  The  apparatus  received  the 
name  '* nitrometer"  because  it  was  originally  employed 
for  the  determination  of  nitrogen  in  nitrates  and  nitrites 
(and  the  corresponding  esters),  and  in  which  the  mer- 
cury served  the  double  purpose  of  confining  fluid  and 
reagent  for  effecting  the  evolution  of  the  nitrogen  in 
the  form  of  NO,  in  the  presence  of  strong  sulphuric 
acid.  It  was,  however,  found  to  be  very  serviceable  in 
other  cases  as  well.  The  name  "  gas-volumeter "  is 
applied  to  those  apparatus  in  which  a  " reduction-tube" 
is  employed  for  mechanically  reducing  the  tempera- 
ture and  pressure  to  0°  C.  and  760  mm. 

The  simple  nitrometer  is  shown  in  fig.  10,  and  its 
most  usual  application,  the  analysis  of  nitrates  and 
nitrites,  will  be  described.  A  is  the  gas-measuring  tube, 
which  may  be  either  cylindrical,  with  the  portion  below 
the  cock  holding  50  cc,  and  graduated  hi  1/10  cc,;  or 


GAS-VOLUMETRY. 


31 


globular  in  form,  with  a  capacity  of  100  to  150  cc., 
the  lower  50  cc.  of  which  are 
contained  within  the  cylin- 
drical part,  graduated  in 
1/10  cc.  The  upper  part  of 
the  tube  bears  a  three-way 
cock,  a,  and  the  funnel,  b. 
A  stout  rubber  tube  connects 
the  lower  end  of  A  with  the 
leveling-tube  B.  A  is  filled 
with  mercury  through  B, 
until  it  enters  b,  the  excess 
being  then  allowed  to  run  off 
through  the  side  tube  at  a. 
The  substance  to  be  exam- 
ined is  then  introduced 
into  b.  Nit  rose  or  sulphuric 
acid  containing  nitric  acid 
is  simply  introduced  with 
a  pipette;  saltpeter  is  in- 
troduced -either  in  substance 
with  a  little  water,  or  in  very  concentrated  solution; 
guncotton,  dynamite,  and  the  like,  are  placed  within 
b  in  substance,  and  dissolved  therein  in  concentrated 
sulphuric  acid.  The  liquids  are  drawn  into  A  by  low- 
ering B  and  cautiously  opening  the  cock  a,  b  being 
then  rinsed  by  pouring  into  it  2  to  3  cc.  of  concen- 
trated sulphuric  acid,  and  drawing  this  into  A  as 
before,  the  operation  being  repeated  once  more,  a  is 
now  closed,  and  A  vigorously  shaken  until  no  further 


FIG.  10. 


32  TECHNO-CHEMICAL  ANALYSIS. 

evolution  of  gas  takes  place.  After  waiting  ten  to 
fifteen  minutes,  in  order  to  allow  the  foam  to  subside 
and  the  temperature  to  become  even  throughout,  the 
gas  in  A  is  brought  under  atmospheric  pressure  by 
raising  B  to  such  a  height  that  the  mercury  in  B  stands 
at  a  somewhat  higher  level  than  in  A,  i.e.,  as  much 
higher  as  the  layer  of  acid  in  A,  hence  corresponding 
to  about  one-seventh  of  the  height  of  the  latter;  it  is 
advisable,  in  fact,  to  have  the  level  slightly  lower,  in 
order  to  create  in  A  a  slight  diminution  of  pressure.  A 
few  drops  of  acid  are  then  poured  into  6,  and  the  cock 
a  opened  very  cautiously,  until  the  acid  running  from 
b  causes  the  liquids  in  A  and  B  to  stand  at  the  same 
height,  and  which  naturally  requires  that  air  be  allowed 
to  enter  A.  The  volume  of  nitric  oxide  in  A  is  then 
read  off,  the  temperature  being  also  read  from  a  ther- 
mometer suspended  quite  close  to  the  apparatus,  while 
the  barometer  is  also  observed;  the  proper  reduction 
is  then  made  to  0°  C.  and  760  mm. 

As  the  gas  in  this  case  may  be  considered  as  perfectly 
dry,  because  of  the  presence  of  the  concentrated  sul- 
phuric acid,  the  formula  for  the  reduction  is  quite  sim- 

273B 
S  (273+  0760' 

Every  cubic  centimeter  of  NO  corresponds  to  0.000625 
grm.  nitrogen,  or  0.001694  grm.  N203,  or  0.002808  grm. 
IIN03,  or  0.003789  grm.  NaN03. 

The  operation  may  also  be  carried  out  by  having  the 
reaction  take  place  in  a  vessel  separate  from  the  meas- 
uring-tube; in  which  case  the  latter  js  then  used  only 


GAS-VOLUMETRY. 


33 


for  measuring  the  gas:      If   the  operation   above  de- 
scribed is  to  be  made,  i.e.,  the  evolution  of  nitric  oxide 
from  nitrate-  or  nitrite  nitrogen,  by  shaking  with  mercury 
and  concentrated  sulphuric  acid,  there  is 
employed  for  the  purpose  -an  ' '  agitation- 
flask"  C  (fig.  11),  arranged  like  the  nitro- 
meter, but  not  graduated,  and  provided 
with  a  separate  leveling-tube,  D.    The  de- 
composition is  effected  just  as  described 
above,  and  the  gas  then  forced  into  A  by 
raising  D  and  lowering  B  and  C,  after  the 
capillary  tubes  at  the  side  of  the  cocks  have 
been  connected,  and  A  filled  to  the  top  with 
mercury.     All  the  gas  is  forced  over,  but 
none  of  the  acid  in  C  must  be  allowed  to 
pass  in  along  with  the  gas.     The  mercury 
in  A  and  B  is  then  brought  to  a  level,  the 
volume  of  gas  in  A  read  off,  thermometric  and  baro- 
metric readings  taken,  and  the  reduction  then  made  to 
0°  C.  and  760  mm. 

For  those  gas-volumetric  operations  in  which  other 
reactions  occur,  use  is  made  of  the  flask  shown  in  fig.  12. 
It  resembles  those  used  in  the  azotometer 
(fig.  9),  and  .is  used  in  an  exactly  similar 
manner.     The  substance  to  be  decomposed 
is  placed    in  the  space    surrounding   the 
inner  cylinder,  while  in  the  latter  is  put 
the  reagent   (usually  hydrogen  peroxide). 
The  flask  is  connected  by  means  of  a  rubber 
tube  with  the  side  tube  of  the  cock  on  A;  the  latter  hav- 


FlQ.  11. 


FIG.  12. 


34 


TECHNO-CHEMICAL  ANALYSIS. 


ing  first  been  filled  with  mercury  up  to  the  cock  by 
raising  B,  care  being  taken  that  the  flask  be  not  warmed 
by  the  hand  during  handling.  By  inclining  the  flask, 
the  reagent  is  caused  to  flow  out  of  the  cylinder  and 
cause  the  evolution  of  gas,  which  expels  a  correspond- 
ing volume  of  air,  and  which  hence  may  be  measured 

after  the  mercury  has  been 
brought  to  a  level  in  A  and  B. 
Under  the  name  gas- 
volumeter  is  understood  appa- 
ratus which  is  provided  with 
a  ' '  reduction-tube,  "  E,  in 
addition  to  the  parts  already 
described,  and  which  is  con- 
nected by  means  of  a  T- 
tube  and  stout  rubber  tubing 
with  A  as  well  as  with  B  (fig. 
13).  E  has  a  capacity  of 
about  130  cc.,  the  upper  ex- 
panded part  holding  90  cc., 
and  the  lower  part  from  90 
to  130  cc.,  graduated  in  1/10 
cc.  The  upper  end  of  the 
tube  may  be  closed  either  by 
a  narrow  capillary  tube  which 
can  be  sealed  by  fusion,  or  it 
may  be  provided  with  a  cock, 
c,  having  a  mercury  seal.  This 
tube  is  made  so  as  to  hold 
exactly  100  cc.  of  air,  either  fully  saturated  with  moisture 


FIG.  13. 


GAS-VOLUMETftY.  35 

or  perfectly  dry,  at  0°  C.  and  760  mm.  This  is  effected  by 
introducing  into  the  tube  a  drop  of  water  (for  moist 
gases),  or  a  drop  of  concentrated  sulphuric  acid  (for  dry 
gases),  while  c  is  open.  B  is  then  raised  or  lowered  so 
that  the  mercury  level  will  show  in  E  the  space  that 
would  be  occupied  by  100  cc.  of  air,  moist  or  dry,  at 
the  prevailing  temperature  and  pressure,  c  is  then 
closed.  If  now  B  is  elevated  until  the  mercury  in  E 
stands  at  the  100-cc.  mark,  then  the  air  will  be  com- 
pressed to  the  volume  it  would  occupy  at  0°  C.  and  760 
mm.  Should  now  any  gas  from  the  " agitation-flask" 
C,  or  from  the  flask  fig.  12,  pass  over  into  A,  and  the  three 
tubes,  A,  E,  and  C,  be  so  arranged  that  the  mercury  in  E 
stands  at  the  100-cc.  mark,  while  that  in  A  is  exactly 
at  the  same  level,  then  the  gas  in  A  will  occupy  the  vol- 
ume that  it  would  have  at  0°  C.  and  760  mm.  In  all 
subsequent  analyses,  consequently,  it  is  possible,  by  the 
use  of  this  arrangement,  to  immediately  effect  the  re- 
duction of  the  gas,  and  to  read  off  at  once  the  volume 
of  gas  without  having  to  take  note  of  the  temperature 
or  atmospheric  pressure,  as  it  requires  but  a  few  mo- 
ments to  bring  the  mercury  to  a  level  in  the  tubes. 

In  addition  to  its  uses  for  the  above-mentioned  de- 
terminations of  nitrates  and  nitrites,  the  nitrometer  or 
gas-volumeter  is  also  of  particular  service  in  two  other 
classes  of  analytical  operations,  namely,  (1)  for  such 
in  which  substances  containing  " active"  oxygen  are 
caused  to  react  with  hydrogen  peroxide,  and  the  lib- 
erated oxygen  measured,  e.g.,  2KMn04+3H2S04-f 
5H202  =K2S04+  2MnS04+  8H20+ 10  0;  or  Mn02H- 


36  TECHNO-CHEMICAL  ANALYSIS. 

H2S04+H202=MnS04+2H20  +  20;  and  (2)  the  de- 
termination of  carbonic  acid  in  carbonates,  the  expul- 
sion of  the  gas  being  accomplished  with  hydrochloric 
acid,  the  completion  of  the  expulsion  requiring  the 
observance  of  certain  rules  which  will  not  be  given  here, 
but  to  which  the  reader  is  referred  in  Lunge's  Chem.- 
Techn.  Untersuchungsmethoden,  I,  p.  142  et  seq. 


SPECIAL  PAET. 


FUELS  AND  HEATING. 

FUELS  are  examined  for  technical  purposes  as  to  their 
fuel-  or  heat-  value.  In  the  case  of  solid  or  liquid  fuels, 
the  bomb- calorimeter  is  usually  employed,  in  the  form  as 
first  devised  by  Berthelot,  or  as  modified  by  Mahler, 
Hempel,  Langbem,  and  others.  The  principle  upon 
which  all  are  constructed  is  the  same,  and  is  as 
follows:  A  strong  steel  vessel,  having  a  capacity  of 
about  250  cc.  (the  bomb),  and  capable  of  resisting  a 
pressure  of  at  least  15  atmospheres  when  closed,  serves 
for  the  combustion  of  the  substance  with  compressed 
oxygen,  which  is  forced  in  under  a  pressure  of  15  atmos- 
pheres or  over.  The  ignition  is  effected  by  means  of 
the  electric  spark,  the  two  platinum  wires  serving  as 
the  poles  passing  through  the  cover,  the  inner  ends  being 
connected  by  a  spiral  of  thin  iron  wire  which  passes 
through  the  substance;  on  closing  the  circuit,  the  iron 
wire  becomes  heated  to  redness,  and  the  combustion 
then  proceeds.  The  bomb  is,  however,  previously 
placed  within  a  properly  insulated  calorimeter  filled 

37 


38  TECHNO-CHEMICAL  ANALYSIS. 

with  water,  and  provided  with  a  stirrer  and  a  ther- 
mometer. The  heat  set  free  by  the  combustion  is 
transferred  to  the  calorimeter,  the  " water  value"  of 
which  has  been  previously  determined,  and,  after  ap- 
plying various  corrections,  the  increase  in  temperature 
of  the  water  ascertained.  For  further  details,  see 
Lunge's  Chem.-Techn.  Untersuchungsmethoden,  I,  p. 
234;  and  particularly  also  Langbein,  Zeitschr.  /.  angew. 
Chemie,  1900,  p.  1227. 

Anthracite  coal,  brown  coal,  etc.,  are,  besides,  exam- 
ined also  as  follows:  The  moisture  is  determined  in  a 
coarsely  powdered  average  sample  by  drying  at  110°  C., 
best  in  a  current  of  carbonic  acid;  furthermore,  a 
determination  of  the  ash  is  made,  as  well  as  of  the 
coke  remaining  on  heating  in  a  covered  platinum  Cruci- 
ble, and  the  sulphur  by  ignition  with  magnesia  and 
soda. 

Gaseous  fuels  are  easily  and  rapidly  examined  by 
means  of  Junkers'  calorimeter,  a  species  of  upright 
tubular  boiler  (see  Lunge,  Chem.-Techn.  Untersu- 
chungsmethoden, I,  p.  213,  and  II,  p.  645). 

The  upper  heat  value  of  a  generator  gas,  the  CO 
and  H2  content  of  which  are  known,  is  approximately 
ascertained  by  means  of  the  following  formula:  1  cm.  = 
30.6(CO  +H2)  cal.,  CO  and  H2  being  replaced  by  the 
volume  percentages  of  the  respective  gases. 

In  all  of  these  cases  the  upper  and  lower  heat  values 
are  differentiated.  The  upper  heat  value,  more  prop- 
erly designated  "heat  of  combustion,"  is  the  total 
heat  liberated  within  the  calorimeter,  including  the 


FUELS  AND  HEATING.  39 

latent  heat  of  the  aqueous  vapor,  as  the  latter  is  of 
course  condensed  in  the  calorimeter  to  water.  This 
latter  amount  is,  however,  of  no  value  practically, 
as  in  all  technical  processes  of  combustion  the  water 
always  escapes  as  vapor.-  The  lower,  or  actual,  heat 
value  is  hence  obtained  when  from  the  upper  heat 
value  we  subtract  the  latent  heat  already  existing  in 
the  fuel  together  with  that  of  the  water  formed  during 
the  combustion.  To  obtain  this  result,  both  the  con- 
tent of  hygroscopic  water  and  the  quantity  present 
in  the  dry  substance  must  be  ascertained  by  analysis. 

Technical  analysis  is  also  extended  to  the  investiga- 
tion of  smoke-gases.  These  are  usually  examined  for 
their  carbonic-acid  content,  which  is  best  done  by  the 
aid  of  the  Orsat  apparatus  (page  12).  With  this, 
should  it  be  necessary,  the  carbonic  oxide  and  oxygen 
may  also  be  determined.  Furthermore,  under  the 
names  "dasymeter,"  "  oekonometer,"  etc.,  apparatus 
have  been  constructed  which  utilize  the  circumstance 
that  the  specific  gravity  of  a  smoke-gas  is  the  higher 
the  greater  the  quantity  of  carbonic  acid  it  contains, 
and  that  by  means  of  a  "gas-balance"  the  carbonic- 
acid  content  may  therefore  be  ascertained  with  suffi- 
cient exactitude  for  practical  purposes  without  analysis, 
by  the  simple  reading  of  an  index. 

WATER. 

Water,  in  technical  analysis,  is  chiefly  considered  in 
reference  to  its  use  in  steam-boilers.  We  have  here 
simply  the  question  of  determining  either  the  total,  or 


40  TECHNO-CtJEMWAL  ANALYSIS. 

several  individually,  of  the  mineral  constituents  that 
remain  on  evaporation  of  the  water.  Organic  impuri- 
ties in  large  quantities,  free  acids,  etc.,  occur  so  seldom 
in  water  that,  for  the  above-mentioned  purposes,  they 
need  scarcely  be  considered.  Alkalies  (carbonates  or 
chlorides),  too,  are  found  in  water  in  very  small  quan- 
tity; water  containing  notable  amounts  of  these  are  in 
fact  classed  among  the  mineral  "  waters,"  and  need  not 
be  considered  here. 

The  constituents  to  which  special  attention  must  be 
paid  are  the  calcium  and  magnesium  compounds,  which 
occur  in  water  as  carbonates  (or  bicarbonates)  and 
sulphates,  and  which  make  the  water  "  hard/'  The 
hardness  is  frequently  indicated  in  degrees,  the  total 
calcium  and  magnesium  compounds  being  expressed 
in  the  terms  of  CaO  equivalent  to  them.  A  German 
degree  of  hardness  corresponds  to  1  part  of  CaO  in 
100,000  parts  of  water.  In  France  a  degree  of  hard- 
ness is  equivalent  to  1  part  of  CaC03  in  100,000;  while 
in  England  ij  is  1  part  of  CaC03  in  70,000  parts  of 
water.  The  sum  of  the  units  of  all  the  earthy  alkalies 
is  designated  as  total  hardness;  the  term  permanent 
hardness  is  employed  to  express  that  which  remains 
after  prolonged  boiling  of  the  water,  filtering,  and 
adding  sufficient  distilled  water  to  bring  the  whole  to 
the  original  volume;  while  the  term  temporary  hardness 
is  used  to  express  the  difference  between  the  total 
and  permanent  hardness,  it  being  chiefly  caused  by 
the  separation  of  calcium  carbonate. 

The  hardness  of  water  was  formerly  generally,  and 


WATER.  41 

is  often  even  yet,  ascertained  by  Clark's  method,  which 
is  based  upon  the  fact  that  on  adding  an  alcoholic 
potassa-soap  solution  to  the  water  to  be  tested,  it 
precipitates  the  salts  of  the  alkaline  earths,  and,  on 
shaking,  affords  no  persistent  foam  antil  the  precipita- 
tion is  perfectly  complete.  The  quantity  of  soap 
solution  used  up  is,  therefore,  a  measure  of  the  hard- 
ness of  the  water.  But  this,  nevertheless,  is  not  directly 
proportional  to  the  quantity  of  soap  solution  used  up: 
it  must  be  ascertained  by  reference  to  tables  prepared 
by  purely  empirical  methods  (see  Lunge,  Chem.-Techn. 
Untersuchungsmethoden,  I,  p. 710),  which,  of  themselves, 
introduce  an  element  of  uncertainty  that  is  even  in- 
creased by  various  other  circumstances.  This  method,  of 
course,  affords  no  indication  as  to  what  individual  sub- 
stances are  present.  If  to  this  be  added  the  fact  that 
the  performance  of  the  test  requires  considerable  time, 
because  the  mixture  must  be  thoroughly  shaken  after 
each  addition  of  soap  solution,  and  towards  the  end 
of  the  operation  a  period  of  five  minutes  must  be 
allowed  to  elapse  between  the  successive  additions  in 
order  to  see  whether  the  foam  persists,  it  will  be  seen 
that  this  method  can  not  be  recommended  in  prefer- 
ence to  the  more  recent  ones,  which  are  not  only  sim- 
pler, but  more  accurate  as  well. 

The  following  methods  are  far  better: 

1.  Determination  of  the  total  alkalinity,  corresponding 

to  the  temporary  hardness,   excepting  in  such  cases 

where   notable   quantities   of  sodium  bicarbonate   are 

present,   as  in  the  case  of   mineral  waters  or   other 


42  TECHNO-CHEMICAL  ANALYSIS. 

waters  which  have  been  treated  with  soda.  A  small 
quantity  of  methyl-orange  solution  is  added  to  200  cc. 
of  the  water  just  to  incipient  yellowness,  and  then 
1/5-normal  hydrochloric  acid  is  added  until  the  color 
changes  to  a  pale  pink.  Every  cubic  centimeter  of  the 
1/5-normal  acid  used  up  is  the  equivalent  of  0.01  grm. 
of  CaC03;  hence  in  200  cc.  of  the  water  0.05  grm.  of 
CaC03  per  liter  is  indicated,  or  2.8  degrees  of  hardness 
on  the  German  scale. 

The  total  hardness  may  already  be  approximately 
ascertained  by  evaporating  100  cc.  of  the  water, 
igniting  the  residue  with  the  addition  of  some  ammo- 
num  carbonate,  and  multiplying  the  weight  of  the 
ignition-residue,  expressed  in  milligrammes,  by  0.56; 
e.g.,  were  0.025  grm.  obtained,  the  hardness  would  be 
25X0.56=14°. 

2.  A  few  drops  of  acid  are  added  to  200  cc.  of 
water  neutralized  as  in  1  with  hydrochloric  acid,  the 
liquid  evaporated  down  to  50  or  60  cc.,  cooled,  then 
washed  into  a  100-cc.  flask,  carefully  neutralized, 
boiled  once  more,  40  cc.  of  a  mixture  of  equal  parts 
of  1/10-normal  NaOH  and  1/10-normal  Na2C03  added, 
the  liquid  again  boiled,  allowed  to  cool,  and  then  made 
up  to  the  mark  with  distilled  water.  The  liquid  is  now 
passed  through  a  filter,  and  the  excess  of  the  alkali 
determined  in  50  cc.  of  the  filtrate  by  titrating  with 
1/10-normal  hydrochloric  acid,  using  methyl  orange  as 
the  indicator.  By  multiplying  the  number  of  cubic 
centimeters  used  up  by  2  and  deducting  the  result 
from  40  cc.,  the  quantity  of  alkali  required  to  precipi- 


WATER.  43 

tate  the  earthy  alkalies  in  200  cc.  of  the  water  is  ascer- 
tained, and  this  multiplied  by  1.4  gives  the  total  hard- 
ness in  German  degrees. 

3.  If  the  earthy  alkalies  obtained  in  1,  calculated  as 
CaO,  be  deducted  from  that  obtained  in  2,  we  obtain  a 
measure  of  the  " permanent"  hardness,  i.e.,  for  the 
calcium  sulphate  present.  In  this  case,  instead  of  the 
German  degree  of  hardness  (or  0.028  per  liter),  we  would 
always  calculate  0.068  gm.  CaS04  per  liter. 

For  the  determination  of  magnesia,  should  this  be 
required,  as  well  as  of  iron,  chlorides,  etc.,  the  usual 
methods  of  analytical  chemistry  are  employed. 


INORGANIC   CHEMICAL   MANUFACTURING   IN- 
DUSTRY. 

SULPHUROUS  AND  SULPHURIC  ACIDS. 

The  raw  materials  that  serve  as  the  source  for  the 
manufacture  of  sulphurous  acid  are  elementary  sul- 
phur, pyrites,  zinc  blende  and  other  sulphides,  and 
also  the  hydrogen  sulphide  obtained  in  the  manufacture 
of  ammonium  sulphate. 

i.  Sulphur. — The  kind  most  usually  to  be  considered 
is  the  Sicilian  crude  sulphur.  It  is  generally  examined 
only  as  to  its  ash  content,  and  for  this  purpose  10  grm. 
are  burned  in  a  tared  porcelain  dish.  It  is  only  occasion- 
ally examined  for  arsenic  (from  which  it  should  be 
perfectly  free),  selenium,  and  bituminous  substances. 
In  very  accurate  analyses  the  sulphur  is  determined 
directly  by  dissolving  in  carbon  disulphide  and  deter- 
mining the  specific  gravity  of  the  solution  (see  Unter- 
suchungsmethoden,  I,  p.  240. 

When  powdered  sulphur  is  to  be  used  for  dusting 
vines,  its  degree  of  fineness  must  be  considered,  and 
this  is  ascertained  by  means  of  Chancel's  sulphurimeter. 
This  apparatus  consists  of  a  well-stoppered  tube  gradu- 
ated in  100  degrees,  and  in  which  5  gm.  of  sulphur 

44 


INORGANIC  CHEMICAL  MANUFACTURES.         45 

are  shaken  with  25  cc.  of  anhydrous  ether,  an  observa- 
tion being  then  made  as  to  at  what  mark  on  the  scale  the 
sulphur  has  settled;  the  finer  the  powder  the  less  will 
it  sink.  Ordinary  ground  sulphur  is  indicated  by  50° 
to  55°,  and  the  finest  quality  by  70°  to  75°,  Chancel. 

Another  form  of  elementary  sulphur  is  gas-sulphur, 
i.e.,  the  gas-purifying  mass  used  in  gas-works,  and 
which  contains,  besides  ferric  oxide,  ammonium  salts, 
cyanogen  compounds,  tar,  etc.,  also  50  per  cent,  and 
more  of  free  sulphur.  A  determination  of  the  total 
sulphur  is  not  necessary  in  this  case,  but  only  that 
which  is  obtained  in  the  form  of  S02  by  combustion. 
For  this  purpose  about  0.4  grm.  of  the  substance  is 
heated  in  a  glass  tube  in  a  current  of  air,  and  the  gas  con- 
ducted into  an  absorption  fluid,  by  which  the  862  is 
retained.  The  most  suitable  liquid  for  this  purpose  is 
hydrogen  peroxide,  the  reaction  taking  place  as  fol- 
lows: H202+S02  =  H2S04.  The  resulting  free  acid  is 
then  titrated  with  normal  soda. 

2.  Pyrites. — These  are  examined  for  moisture  by 
drying  at  105°  C.;  but  particularly  for  its  sulphur  con- 
tent. This  is  most  frequently  accomplished  by  de- 
composition by  the  wet  way,  using  a  mixture  of  3  vol- 
umes of  nitric  acid  sp.  gr.  1.4  and  1  volume  of  concen- 
trated hydrochloric  acid.  Of  this  mixture  10  cc.  are 
taken  for  0.5  gin.  of  the  pyrites,  the  operation  being 
conducted  at  a  moderate  heat,  until  the  reaction  is  at 
an  end  and  no  more  particles  of  unoxidized  sulphur 
are  visible.  The  mass  is  then  evaporated  to  dryness, 
and  the  nitric  acid  decomposed  by  adding  hydrochloric 


46  TECHNO-CHEMICAL  ANALYSIS. 

acid  and  again  evaporating,  after  which  the  residue  is 
dissolved  in  diluted  hydrochloric  acid.  The  iron  is 
then  removed  by  precipitating  with  ammonia  in  mod- 
erate excess  at  a  temperature  between  60°  and  70°  C., 
filtering  off  and  thoroughly  washing  the  ferric  hydrox- 
ide, and  precipitating  the  sulphuric  acid  in  the  filtrate 
by  boiling  with  the  gradual  addition  of  barium-chloride 
solution.  The  clear  liquid  may  already  be  decanted 
through  a  filter  in  from  twenty  to  thirty  minutes;  the 
precipitate  of  barium  sulphate,  however,  is  first  washed 
by  decantation  with  boiling  water,  then  thoroughly 
washed  on  the  filter  itself,  dried,  and  ignited,  the  filter 
too  being  burned  in  a  platinum  spiral  or  in  a  crucible. 
The  ignited  BaS04  should  have  a  pure  white  color,  and 
be  in  very  fine,  pulverulent  form;  1  part  corresponds 
to  0.1373  part  sulphur. 

The  decomposition  of  pyrites  is  also  frequently  ac- 
complished by  the  dry  way,  the  method  formerly  em- 
ployed being  fusion  with  soda  and  saltpeter  or  potassium 
chlorate,  while  nowadays  the  fusion  is  effected  with 
sodium  peroxide.  In  this  case  the  iron  remains  as  a 
residue  when  the  fused  mass  is  dissolved;  for  the  rest, 
the  process  is  then  carried  out  as  above  detailed. 

Many  methods  have  been  devised  for  the  volumetric 
determination  of  combined  sulphuric  acid,  but  none  of 
them  are  used  for  the  accurate  determination  of  sul- 
phur in  the  ores  containing  it;  nor  do  they  afford  any 
great  saving  of  time  as  compared  with  the  gravimetric 
methods,  in  practiced  hands,  for  determining  the 
sulphur  as  barium  sulphate, 


INORGANIC  CHEMICAL  MANUFACTURES.         47 

At  times  arsenic  also  is  determined  in  pyrites,  and 
best  by  fusion  with  soda  and  saltpeter,  whereby  the 
arsenic  is  converted  into  an  arsenate,  which  is  then 
precipitated  with  silver  nitrate  as  silver  arsenate.  The 
precipitate  is  washed,  dissolved  in  nitric  acid,  and  the 
silver  hi  it  determined  by  titration  with  ammonium- 
sulphocyanate  solution,  using  ferric  sulphate  as  the 
indicator.  1  cc.  of  a  1/10-normal  sulphocyanate 
solution  indicates  0.0025  gm.  of  arsenic. 

Copper  is  most  usually  determined  in  pyrites  by  elec- 
trolytic methods,  after  it  has  been  brought  into  solution 
by  decomposing  the  ore  with  nitric  acid,  or  in  some 
other  manner.  Zinc,  carbonates  of  the  earths,  and 
carbon  are  but  seldom  determined. 

3.  Zinc  blende  is  decomposed  just  like  pyrites,  and 
the  sulphur  in  it  similarly  determined,  but  in  addition 
the  zinc  also,  most  generally  by  titration  with  sodium- 
sulphide  solution.  This  must,  however,  be  preceded 
by  a  rather  troublesome  purification,  in  order  to  remove 
any  lead,  cadmium,  etc.,  present. 

In  the  manufacture  of  sulphuric  acid  there  serve  as 
raw  materials,  furthermore,  sodium  nitrate  and  nitric 
acid,  which  are  to  be  tested  as  will  be  detailed  in  the 
chapter  devoted  to  the  manufacture  of  nitric  acid. 

For  the  factory  control  we  require: 

1.  The  examination  of  the  cinders  of  the  pyrites  or 
blende  for  any  residual  sulphur.  For  this  purpose 
the  decomposition  is  usually  effected  by  the  dry  way. 
The  decomposition  is  most  speedily  accomplished  by 
fusion  with  a  weighed  quantity  of  sodium  bicarbonate 


48  TECHNO-CHEM1CAL  ANALYSIS. 

of  known  titer  in  a  nickel  crucible,  and  at  a  gentle 
heat,  whereby  the  sulphur  is  converted  into  sulphate 
by  the  atmospheric  oxygen,  and  at  the  expense  of  the 
sodium  bicarbonate,  so  that  the  quantity  formed  may 
be  determined  by  titrating  back  the  filtered  solution 
of  the  melt  with  normal  hydrochloric  acid  and  methyl 
orange.  When  effecting  the  solution,  however,  a  large 
quantity  of  sodium  chloride  must  be  added,  other- 
wise finely  divided  ferric  o:dde  always  passes  through 
the  filter,  and  renders  titration  almost  impossi- 
ble. 

This  process  can  not  be  employed,  moreover,  for 
cinders  from  pyrites  rich  in  zinc,  or  from  zinc  blende, 
but  the  procedure  must  be  that  employed  in  the  case 
of  zinc  blende  (page  47). 

2.  The  calcination  gases  are  examined  as  to  their 
content  of  sulphur  dioxide  by  Reich's  method,  page  23, 
and  also  for  their  total  acid  content  by  Lunge's  method, 
as  detailed  on  page  26. 

3.  The  acid  issuing  from  the  foot  of  the  Gay-Lussac 
towers  during  the  manufacture  of  sulphuric  acid,  and 
known  as  "nitrose,"  must  be  examined  as  to  the  con- 
tent of  nitrogen  acids;  and  so  too  must  the  chamber 
acids  be  frequently  examined.     It  is  usually  sufficient 
to  determine  the  nitrous  acid  which,  in  the  form  of  nitro- 
sylsulphonic  acid,  S05NH,  is  dissolved  in  the  sulphuric 
acid.    This  is  done  by  allowing  the  acid  to  be  tested 
to  run  from  a  burette  into  a  measured  volume  of 
standardized    potassium-permanganate    solution    until 
the  latter  is  just  decolorized,  nitric  acid  being  formed 


INORGANIC  CHEMICAL  MANUFACTUR1 
thereby;  hence  every  16  of  oxygen  yielded  by 

•^ 

manganate  solution  indicate  47  of  HN02. 

The  total  nitrogen,  i.e.,  that  from  the  nitric  and 
nitrous  acids,  is  determined  in  a  nitrometer  (see  page 
30). 

The  end-products  of  this  industry  are,  besides  liquid 
sulphur  dioxide,  which  will  not  be  here  considered, 
the  following: 

I.  Lyes  used  in  the  manufacture  of  sulphite  cellulose. 
In  these  the  total  content  of  sulphurous  acid  is  ascer- 
tained by  titration  with  iodine  solution;    and  the  free 
sulphurous  acid  (i.e.,  that  in  excess  of  what  is  required 
to  form    NaSOs)  by  titrating  with  normal  soda-lye, 
using  phenolphtalein  as  the  indicator. 

II.  Sulphuric  acids  of  various  strengths.     The  value 
of  these  depends,  first  and  foremost,  upon  their  content 
of  actual  sulphuric  acid,  H2S04;    and  in  the  case  of 
fuming   sulphuric   acid,    on   the   content   of   sulphuric 
anhydride,    S03.     In   addition,    however,    the   impuri- 
ties in  sulphuric  acid  must  in  many  cases  be  deter- 
mined also. 

The  sulphuric-acid  content  is  in  most  cases  deter- 
mined quite  simply  by  taking  the  specific  gravity 
with  an  araeometer  which  shows  the  strength  in  either 
degrees  or  percentage  of  H2S04.  Of  the  araeometers, 
the  one  most  generally  used  is  that  of  Baume.  The 
following  table  shows  the  relationship  between  the 
specific  gravity,  the  sulphuric-acid  content,  and  the 
degrees  Baume: 


50 


TECHNO-CHEMICAL  ANALYSIS. 


4 

IS  > 
«  g 

If 

gl 

X* 

I 

Per  Cent. 

H2S04. 

>> 

«! 

11 

02 

VflJ 

*>Q3 

Per  Cent. 
HaSO,. 

>> 
0 

£j  c3 

\& 

o>  g 

jppo 

Per  Cent. 
H2S04. 

.01 

1.4 

1.57 

1.31 

34.2 

40.35 

1.60 

54.1 

68.51 

.02 

2.7 

3.03 

1.32 

35.0 

41.50 

1.61 

54.7 

69.43 

.03 

4.1 

4.49 

1.33 

35.8 

42.66 

1.62 

55.2 

70.32 

.04 

5.4 

5.96 

1.34 

36.6 

43.74 

.63 

55.8 

71.16 

.05 

6.7 

7.37 

1.35 

37.4 

44.82 

.64 

56.3 

71.99 

.06 

8.0 

8.77 

1.36 

38.2 

45.88 

.65 

56.9 

72.81 

1.07 

9.4 

10.19 

1.37 

39.0 

46.94 

.66 

57.4 

73.64 

1.08 

10.6 

11.60 

1.38 

39.8 

48.00 

.67 

57.9 

74.51 

1.09 

11.9 

13.00 

.39 

40.5 

49.06 

.68 

58.4 

75.42 

1.10 

13.3 

14.35 

.40 

41.2 

50.11 

.69 

58.9 

76.30 

1.11 

14.2 

15.71 

.41 

42.0 

51.15 

.70 

59.5 

77.17 

1.12 

15.4 

17.01 

.42 

42.7 

52.15 

.71 

60.0 

78.04 

1.13 

16.5 

18.31 

.43 

43.4 

53.11 

.72 

60.4 

78.92 

1.14 

17.7 

19.61 

.44 

44.1 

54.07 

.73 

60.9 

79.80 

1.15 

18.8 

20.91 

.45 

44.8 

55.03 

.74 

61.4 

80.68 

1.16 

19.8 

22.19 

.46 

45.4 

55.97 

.75 

61.8 

81.56 

1.17 

20.9 

23.47 

.47 

46.1 

56.90 

.76 

62.3 

82.44 

1.18 

22.0 

24.76 

.48 

46.8 

57.83 

.77 

62.8 

83.32 

1.19 

23.0 

26.01 

.49 

47.4 

58.74 

.78 

63.2 

84.50 

1.20 

24.0 

27.32 

.50 

48.1 

59.70 

.79 

63.7 

85.70 

1.21 

25.0 

28.58 

.51 

48.7 

60.65 

.80 

64.2 

86.80 

1.22 

26.0 

29.84 

.52 

49.4 

61.59 

.81 

64.6 

88.30 

1.23 

26.9 

31.11 

.53 

50.0 

62.63 

.820 

65.0 

90.50 

1.24 

27.9 

32.28 

.54 

50.6 

63.43 

.825 

65.2 

90.80 

1.25 

28.8 

33.43 

.55 

51.2 

64.26 

.83 

65.5 

92.10 

1.26 

29.7 

34.57 

.56 

51.8 

65.08 

1.835 

65.7 

93.43 

1.27 

30.6 

35.71 

.57 

52.4 

65.90 

1.840 

65.9 

95.60 

1.28 

31.5 

36.87 

1.58 

53.0 

66.71 

1.8415 

— 

97.70 

1.29 

32.4 

38.03 

1.59 

53.6 

67.59 

1.8385 

— 

99.95 

1.30 

33.3 

39.19 

The  specific  gravity  must  be  taken  at  15°  C.;  at 
other  temperatures  a  correction  must  be  made.  Of 
course,  the  table  holds  good  only  for  perfectly  pure 
acids,  although  it  is  only  in  the  highest  concentrations 
that  there  are  notable  differences  in  strength  between  the 
pure  and  commercial  acids  of  the  same  specific  gravity. 

A  more  accurate  determination  of  the  sulphuric  acid 
is  effected  by  titration.  This  is,  above  all,  necessary  in 


INORGANIC  CHEMICAL  MANUFACTURES.         51 

the  case  of  the  highly  concentrated  acids,  in  which  the 
specific  gravity  no  longer  increases  in  proportion  to 
the  concentration.  The  titration  of  the  sulphuric  acid 
is  accomplished  most  simply,  and  best,  by  means  of 
a  normal  solution  of  caustic  soda,  with  methyl  orange 
as  the  indicator,  whereby  the  carbonic-acid  content 
of  the  soda-lye  need  not  be  considered,  which  thus 
permits  the  operation  to  be  carried  out  very  rapidly, 
and  in  the  cold.  This  indicator  is  reddened  by  strong 
acids;  on  the  other  hand,  towards  weak  acids,  like 
carbonic  acid,  it  is  insensitive.  Alkalies  color  it  yellow. 
The  end  of  the  reaction  is  indicated  by  a  brownish, 
mixed  color,  which  is  changed  by  a  drop  of  acid 
to  a  reddish,  and  by  a  drop  of  alkali  to  a  yellowish, 
color. 

The  soda  solution  used  for  titrating  is  first  standard- 
ized by  normal  hydrochloric  or  sulphuric  acid,  using 
chemically  pure  soda  freed  from  moisture  and  carbonic 
acid  by  heating  at  300°  C. 

Other  operators  prefer  to  use  phenolphtalein,  which 
affords  a  very  sharp  color  change  from  colorless  to  a 
rose-red  as  soon  as  the  acid  is  neutralized  by  the  alkali 
and  a  slight  excess  of  the  latter  supervenes.  As  phenol- 
phtalein, however,  is  decolorized  by  carbonic  acid,  the 
titration  must  be  carried  out  while  the  liquid  is  con- 
stantly boiling,  which  makes  it  absolutely  necessary 
to  discard  the  use  of  glass  vessels,  and  which  thus 
makes  the  operation  more  inconvenient  and  protracted. 
Or,  it  is  necessary  to  employ  perfectly  pure,  carbonic- 
acid-free  lyes,  which  in  the  case  of  soda-lye  it  is  a  matter 


52  TECHNO-CHEMICAL  ANALYSIS. 

of  some  difficulty  to  assure.  It  is  much  more  convenient 
to  employ  baryta  solution,  which  must  not,  however, 
be  prepared  of  a  definite  strength,  but  must  be  standard- 
ized empirically.  On  this  account  the  employment  of 
methyl  orange  is  greatly  to  be  preferred,  although  it 
requires  somewhat  more  experience  to  recognize  when 
the  color  change  takes  place. 

It  must  not  be  overlooked  that  any  add  impurities  in 
the  sulphuric  acid  (nitric  acid,  hydrochloric  acid)  are 
also  calculated  as  sulphuric  acid  when  titrating;  these 
must  be  separately  determined,  therefore,  and  the 
proper  allowance  made  for  them. 

Of  the  impurities  in  sulphuric  acid  of  commerce,  the 
following  are  the  most  frequently  to  be  considered: 

a.  Nitrogen  acids  (nitric  acid  and  nitrous  acid,  the 
latter  being  present  in  the  form  of  nitrosylsulphuric  acid, 
SOsNH).    These   acids   are   best   determined   qualita- 
tively by  adding  a  1-per-cent.  solution  of  diphenylamine 
in  concentrated  sulphuric  acid,  which  develops  a  blue 
coloration.    The  quantitative  determination  is  effected 
as  in  the  case  of  "nitrose"  (see  page  48). 

b.  Selenium  is  recognized  by  adding  a  solution  of 
ferrous  sulphate,  with  which  it  affords  a  brownish-red 
precipitate. 

c.  Lead  is  detected  by  diluting  with  water,  very  small 
quantities  being  precipitated,  on  adding  alcohol,  in  the 
form  of  lead  sulphate,  which  should  be  further  examined 
with  the  blowpipe. 

d.  Iron  is  recognized  by  boiling  with  a  drop  of  pure 
nitric  acid,  diluting,  cooling,  and  adding  a  solution  of 


INORGANIC  CHEMICAL       ANUFACTURES.         63 

potassium  sulphocyanate;  a  red  color  develops  if  iron 
is  present. 

e.  Arsenic,  above  all,  should  not  be  present  in  sul- 
phuric acid  which,  in  remedial  agents,  may  be  ingested 
into  the  human  system.  - 

A  simple,  and  usually  satisfactory,  test  for  it  is  that 
of  Marsh,  which  is  performed  as  follows:  A  piece  of 
chemically  pure  zinc  is  introduced  into  a  flask  pro- 
vided with  a  two-holed  cork,  one  hole  of  which  bears 
a  funnel  reaching  almost  to  the  bottom  of  the  flask. 
Through  this  funnel  a  little  pure  diluted  sulphuric  acid 
is  poured,  and  the  hydrogen  evolved  escapes  through 
a  tube  bent  at  a  right  angle,  and  inserted  in  the  other 
hole  in  the  cork;  the  outer  end  of  the  tube  is  drawn  out 
to  a  point.  When  it  is  certain  that  all  the  air  has  been 
expelled  from  the  flask,  and  that  no  explosion  is  there- 
fore likely,  the  jet  of  gas  issuing  from  the  tube  is  ignited, 
and  the  flame  allowed  to  impinge  on  a  white  porcelain 
surface.  A  little  of  the  acid  to  be  tested  (and  pre- 
viously diluted)  is  now  poured  in.  If  any  arsenic  is 
present,  a  black  spot  will  form  on  the  porcelain. 

For  more  accurate  purposes  the  Marsh-Berzelius  test 
is  employed.  In  this  the  procedure  is  the  same  as 
above,  but  the  gas  is  freed  from  hydrogen  sulphide  by 
lead  acetate,  then  dried  by  calcium  chloride,  and  passed 
through  a  tube  of  difficultly  fusible  glass  which  is  heated 
to  redness  by  a  gas-flame.  If  any  arsenic  is  present, 
the  arsine  formed  is  decomposed  at  the  heated  point, 
and  there  is  deposited  a  grayish-black  mirror,  the  in- 
tensity of  which  is  a  measure  of  the  quantity  of  arsenic 


54  TECHNO-CHEMWAL  ANALYSIS. 

present.  It  is  imperatively  necessary,  however,  under 
all  circumstances,  that  a  parallel  test  be  made  with 
pure  acid  in  order  to  be  certain  that  neither  the  zinc 
nor  any  other  substance  that  may  be  present  gives  the 
arsenic  test. 

Reinsch's  test  is  also  frequently  used.  This  consists 
in  heating  the  solution  with  a  piece  of  bright  copper 
foil,  which,  if  arsenic  is  present,  becomes  coated  with  a 
grayish  deposit  of  copper  arsenide.  In  Gutzeit's  test 
the  acid  is  treated  with  arsenic-free  zinc  in  a  test-tube 
covered  with  a  cap  of  filter-paper  on  which  a  drop  of  a 
5-per-cent.  silver-nitrate  solution  has  been  allowed  to 
dry;  if  arsenic  is  present  the  spot  first  becomes  yellow,, 
then  black.  It  is  best  to  place  under  the  cap  a  plug 
of  cotton  moistened  with  lead-acetate  solution. 

Fuming  sulphuric  acid  (oil  of  vitriol)  is  weighed  off 
in  a  small  glass  bulb  provided  with  two  long-drawn-out 
points,  or  in  a  pipette  provided  with  a  glass  cock,  then 
allowed  to  run  out  into  a  large  excess  of  water,  and  the 
total  acid  determined  by  titration.  This  is  calculated 
as  S03;  the  remainder  is  taken  as  water,  and  for  every 
18  parts  of  water  there  are  calculated  80  parts  of  S03, 
the  residual  S03  being  calculated  as  free  anhydride. 
This,  however,  assumes  that  there  are  no  other  im- 
purities present  which,  otherwise,  must  be  determined 
and  deducted  from  the  acid  calculated  from  the  water 
difference  as  above. 


INORGANIC  CHEMICAL  MANUFACTURES.         55 


NITRIC  ACID. 

Of  the  raw  materials,  saltpeter  and  sulphuric  acid, 
the  latter  has  already  been  mentioned  (see  page  49 
et  seq.). 

Saltpeter  (soda-saltpeter,  Chili  saltpeter)  is  fre- 
quently examined  only  as  to  its  refraction,  i.e.,  for  its 
content  of  sodium  chloride,  sodium  sulphate,  water, 
and  insoluble  substances,  all  else  being  assumed  to  be 
sodium  nitrate.  This  is  decidedly  improper,  because 
any  potassium  nitrate,  should  this  be  present,  must  be 
regarded  as  injurious,  for,  on  account  of  its  higher 
atomic  weight,  it  yields  less  nitric  acid  than  does  sodium 
nitrate.  Furthermore,  the  perchlorate  (and  what  is  of 
less  importance,  the  iodate)  is  also  here  calculated  as 
nitrate.  In  spite  of  this,  however,  this  mode  of  " analy- 
sis "  is  still  widely  used  as  a  standard  in  the  wholesale 
trade. 

The  moisture  is  determined  by  drying  the  saltpeter 
at  130°  C.;  and  the  substances  insoluble  in  water  by 
dissolving  50  grm.,  filtering,  washing,  and  drying  the 
residue  on  a  tared  filter  at  130°  C.  The  solution  is 
made  up  to  one  liter,  and  the  NaCl  and  Na2S04  in  it 
determined  by  the  usual  methods. 

Far  more  accurate,  however,  is  the  direct  determina- 
tion of  the  nitrate  nitrogen,  which  is  the  procedure 
always  followed  by  chemical  manufacturers  and  agri- 
cultural chemists,  and  for  which  the  following  methods 
are  chiefly  used: 


56  TECHNO-CHEMICAL  ANALYSIS. 

1.  Ulsch's  Method. — Dissolve  20  grm.  of  the  saltpeter 
in  sufficient  water  to  make  one  liter,  and  pipette  off  50 
cc.  (equivalent  to  1  grm.  of  substance)  into  a  liter  flask 
which  is  to  be  covered  with  a  funnel.     To  the  con- 
tents add  1  grm.  powdered  iron  (iron-by-hydrogen)  and 
20  grm.  sulphuric  acid  diluted  with  twice  its  weight  of 
water,  and  heat  for  ten  minutes  to  boiling,  whereby  all 
the    nitrate    is    converted    into    ammonium    sulphate. 
Now  add  150  cc.  water  and  50  cc.  of  caustic  soda-lye 
of  sp.  gr.  1.25,  close  the  flask  with  a  rubber  stopper 
bearing  a  tube  expanded  above  the  stopper  into  a  bulb, 
and  reaching  into  a  receiver  containing  normal  hydro- 
chloric acid.    The  flask  is  then  heated  until  all  the 
ammonia  is  expelled,  and  absorbed  by  the  acid  in  the 
receiver.     The  acid  is  titrated  like  normal  lye,  with 
methyl  orange.     The  hydrochloric  acid  used  up  corre- 
sponds to  the  saltpeter  content,  every  cubic  centimeter 
of  1/5-normal  acid  being  equivalent  to  0.01702  gm.  of 
NaN03.     1    gm.    of    sodium    nitrate    would     require 
58.75  cc.  of  the  acid. 

2.  Lunge's  Nitrometric  Method. — The  apparatus  best 
adapted  for  this  is  the  nitrometer  with  agitation  vessel 
described   on  page   33,  and  which   is  best  converted 
into  a  gas- volumeter  by  adding  a  "  reduction"  tube, 
so  as  to  make  it  unnecessary  to  take  account  of  the 
temperature  and  atmospheric  pressure.    Using  a  gas- 
measuring  tube  having  a  capacity  of  130  cc.,  weigh 
off  0.35  grm.  of  the  saltpeter  and  place  it  in  the  beaker 
of  the  agitation  vessel,  and  then  proceed  as  already  de- 
tailed (loc.  cit.).    Every  cubic  centimeter  of  the  nitric 


INORGANIC  CHEMICAL  MANUFACTURES.         57 

oxide  evolved,  dried,  and  reduced  to  0°  C.  and  760 
mm.  indicates  0.003789  grm.  of  NaN03. 

3.  Schlosing-Grandeau- Wagner's  Method. — This  con- 
sists in  boiling  a  liquid  containing  a  nitrate  with  hydro- 
chloric acid  and  ferric  chloride,  the  total  nitrogen  being 
thus  evolved  as  nitric  oxide  which  is  measured  over 
water,  the  NaN03  being  then  calculated  as  in  the 
method  previously  described. 

Determination  of  Perchlorate.  —  Almost  all  of  the 
methods  known  are  based  upon  the  reduction  of  the 
perchlorate  to  chloride  and  its  determination  in  this 
form,  in  which  case,  of  course,  the  chloride  originally 
present  must  be  deducted  from  the  total.  The  best 
mode  of  procedure  is  to  fuse  the  saltpeter  in  an  iron  or 
nickel  crucible  with  soda,  generally  also  with  the  addi- 
tion of  some  other  substance,  like  manganese  dioxide 
or  powdered  iron,  whereby  the  KC104  is  converted  into 
KC1,  which  is  then  determined  either  gravimetrically 
or  volume trically. 

The  nitric  acid  itself  is  next  examined  as  to  its  con- 
tent of  HN03,  and  frequently  only  by  means  of  the 
araeometer.  The  table  on  p.  58  gives  the  specific 
gravities  of  perfectly  pure  nitric  acid  of  varying 
strengths;  for  the  comparison  between  degrees  Baume 
and  specific  gravities  see  the  sulphuric-acid  table  page 
50. 

In  the  case  of  nitric  acid,  however,  the  employment 
of  the  araeometer  introduces  far  greater  errors  than  when 
it  is  used  for  sulphuric  acid,  hydrochloric  acid,  and  in 
most  other  cases,  as  the  concentrated  nitric  acids  as  a 


58 


TECHNO-CHEMICAL  ANALYSIS. 


Specific 
Grav- 
ity. 

Per 

Cent. 
HNO3. 

Specific 
Grav- 
ity. 

Per 
Cent. 
HNO3. 

Specific 
Grav- 
ity. 

Per 
Cent. 
HNO3. 

Specific 
Grav- 
ity. 

Per 

Cent. 
HNC-3. 

1.01 

1.90 

1.14 

23.31 

1.27 

42.87 

1.40 

65.30 

1.02 

3.70 

1.15 

24.84 

.28 

44.41 

1.41 

67.50 

1.03 

5.50 

1.16 

26.36 

.29 

45.95 

1.42 

69.80 

1.04 

7.26 

1.17 

27.88 

.30 

47.49 

1.43 

72.17 

1.05 

8.99 

1.18 

29.38 

.31 

49.07 

1.44 

74.68 

1.06 

10.68 

1.19 

30.88 

.32 

50.71 

1.45 

77.28 

1.07 

12.33 

1.20 

32.36 

.33 

52.37 

1.46 

79.98 

1.08 

13.95 

1.21 

33.82 

1.34 

54.07 

1.47 

82.90 

1.09 

15.53 

1.22 

35.28 

1.35 

55.79 

1.48 

86.05 

1.10 

17.11 

1.23 

36.78 

1.36 

57.57 

1.49 

89.50 

1  11 

18.67 

1.24 

38.29 

1.37 

59.39 

1.50 

94.09 

1.12 

20.23 

1.25 

39.82 

1.38 

61.27 

1.51 

98.10 

1.13 

21.77 

1.26 

41.34 

1.39 

63.23 

1.52 

99.67 

rule  always  contain  nitrogen  tetroxide  in  solution,  the 
quantity  being  seldom  less  than  1  per  cent.,  but  more 
generally  several  per  cent.,  which  makes  its  strength 
when  taken  with  the  araeometer  seem  greater  than  it 
actually  is.  It  is  hence  more  frequently  necessary  to 
resort  to  titration  in  the  case  of  nitric  acid  than  in  the 
case  of  sulphuric  acid,  the  titration  being  carried  out  as 
detailed  under  Sulphuric  Acid  (see  page  50  et  seq.).  It 
must  not  be  overlooked,  however,  that  the  nitrogen  di- 
oxide also  exerts  an  action  in  this  case,  and  that  besides 
making  a  determination  of  the  total  acid  by  means  of 
normal  alkali,  the  nitrogen  dioxide  must  also  be  deter- 
mined. This  is  accomplished  by  running  the  acid  into 
a  measured  quantity  of  titrated  potassium-perman- 
ganate solution,  just  as  in  titrating  "  nitrose"  (page  48). 
Every  16  parts  of  oxygen  given  up  by  the  permanga- 
nate indicates  0.09208  of  N204. 

Mixtures  of  sulphuric  acid  with  nitric  acid  and  lower 
nitrogen  acids,   such  as  are  technically  employed  in 


INORGANIC  CHEMICAL  MANUFACTURES.         59 

the  form  of  mixed  acid  or  waste  acid  in  the  manufacture 
of  tar  dyes  and  explosives,  are  examined  as  follows : 

The  sulphuric  acid  is  first  determined  by  heating 
2  to  3  grm.  with  the  addition  of  a  little  water  on  the 
water-bath,  until  the  nitrous  odors  have  ceased,  when 
only  sulphuric  acid  will  be  present,  which  is  then 
titrated  with  normal  soda  and  methyl  orange.  The 
lower  nitrogen  acids  are  determined,  as  detailed  on 
page  48,  by  running  in  the  acid  into  permanganate 
solution,  and  calculating  them  as  N204.  The  nitric 
acid  is  found  by  titrating  the  total  acid  and  deducting 
from  it  the  sulphuric  acid  and  the  N204  found  as  above. 
The  titration  may  be  effected  by  means  of  methyl 
orange,  even  though  the  indicator  is  rapidly  decom- 
posed by  nitrous  acid,  if  the  methyl  orange  is  added  just 
before  the  neutralization  with  soda,  or  if  the  acid  be 
supersaturated  with  the  soda,  the  indicator  then  added, 
and  the  liquid  titrated  back  with  normal  acid. 

SULPHATE. 

By  this  designation  is  understood  both  potassium 
sulphate  and  sodium  sulphate,  which  are  obtained  by 
decomposing  NaCl  or  KC1  with  sulphuric  acid,  with 
the  evolution  of  hydrochloric  acid.  The  chlorides  hence 
constitute  the  raw  materials  from  which  the  products 
are  obtained. 

Common  Salt  (Rock  Salt). — This  is  examined  chiefly 
for  its  moisture  content  (by  cautiously  heating,  because 
it  crepitates) ,  and  for  calcium  sulphate,  and  occasionally 
also  for  magnesia. 


60  TECHNO-CHEMICAL  ANALYSIS. 

Denaturized  salt  may  contain  various  substances ;  the 
one  here  considered  is  sodium  sulphate.  The  deter- 
mination is  most  simply  made  by  estimating  the  chlorine 
of  the  chloride  as  below  detailed. 

Potassium  Chloride. — See  under  potassium  salts. 

Sulphate. — One  grm.  is  usually  examined  for  free 
acid,  by  adding  normal  soda  and  methyl  orange  to 
neutralization.  The  total  acidity  is  calculated  as  S0.3, 
including  that  due  to  HC1,  NaHS04,  Fe2(S04)3,  etc., 
present. 

Sodium  Chloride. — Neutralize  with  a  quantity  of 
soda  equal  to  that  employed  in  1,  add  a  little  potassiurn- 
chromate  solution,  and  titrate  with  decinormal  silver- 
nitrate  solution;  1  cc.  of  the  latter  corresponds  to 
0.00585  grm.  NaCl. 

The  sulphate  to  be  used  in  the  manufacture  of  the 
finer  kinds  of  glassware  is  also  examined  as  to  its  iron 
content,  by  reducing  the  iron  salt  with  sulphuric  acid 
and  zinc  to  a  ferrous  condition,  and  then  titrating  with 
potassium  permanganate. 

HYDROCHLORIC  ACID. 

In  the  factory  control  of  the  manufacture  of  hydro- 
chloric acid  the  chimney-gases  must  be  examined  as 
to  their  content  of  acid,  which  is  to  be  calculated  as 
HC1.  A  certain  quantity  of  the  chimney-gases  is  drawn 
off  and  passed  through  water,  in  which  the  S02  present 
in  the  gases  is  directly  oxidized  to  H2S04  by  means  of 
chlorine-free  hydrogen  peroxide,  and  the  total  acid  deter- 
mined by  titrating  with  soda-lye  and  methyl  orange.  If 


INORGANIC  CHEMICAL  MANUFACTURES. 


61 


necessary,  the  chloride  content  is  separately  deter- 
mined by  titrating  with  silver  nitrate  (see  above  under 
Sodium  Chloride). 

Hydrochloric  acid  itself  is  usually  examined  as  to  its 
acid  strength  by  means  of  the  araeometer,  the  following 
table  being  employed  for  the  purpose  (for  the  com- 
parison between  the  Baume  degrees  and  the  specific 
gravities,  see  under  Sulphuric  Acid,  page  50) ;  the  table 
serves,  of  course,  only  for  pure  acids,  and  at  the  tem- 
perature of  15°  C. 


Specific 

Per 

Specific 

Per 

Specific 

Per 

Specific 

Per 

Grav- 

Cent. 

Grav- 

Cent. 

Grav- 

Cent. 

Grav- 

Cent. 

ity. 

HC1. 

ity. 

HC1. 

ity. 

HC1. 

ity. 

HC1. 

1.01 

2.14 

1.06 

12.19 

1.11 

21.92 

1.16 

31.52 

1.02 

4.13 

1.07 

14.17 

1.12 

23.82 

1.17 

33.46 

1.03 

6.15 

1.08 

16.15 

1.13 

25.75 

1.18 

35.39 

1.04 

8.16 

1.09 

18.11 

1.14 

27.66 

1.19 

37.23 

1.05 

10.17 

1.10 

20.01 

1.15 

29.57 

1.20 

39.11 

The  hydrochloric  acid  may,  of  course,  be  titrated 
with  soda-lye,  as  in  the  case  of  sulphuric  acid  (p.  49  et 
seq.),  when  the  free  sulphuric  acid  present  is  also  cal- 
culated as  hydrochloric  acid;  or  by  neutralizing  with 
sodium  carbonate  and  titrating  with  potassium  chromate 
and  silver  solution  (see  page  60) . 

Of  the  impurities,  special  attention  is  directed  to 
arsenic  (see  page  53),  iron  (page  52),  and  sulphuric 
acid  (which  is  to  be  determined  as  BaS04,  see  pp.  45  and 
46),  taking  care  not  to  overlook  any  Na2S04  that  may 
remain  in  the  evaporation-residue). 


62  TECHNO-CHEMICAL  ANALYSIS. 

SODA. 

The  raw  materials  for  the  manufacture  of  soda  by 
the  Leblanc  process  are  sulphate  (page  59),  limestone 
(page  67),  and  coal  (page  38). 

For  the  factory  control  in  this  process  the  crude  soda- 
ash  melt  is  examined  as  to  its  physical  characteristics, 
and  then  chemically,  chiefly  for  its  content  of  alkali,  by 
titrating  the  solution  with  normal  acid  and  methyl 
orange;  furthermore  for  its  content  of  sodium  sul- 
phide, by  titrating  with  iodine  solution  (1  cc.  N-iodine 
solution  is  the  equivalent  of  0.003908  Na2S);  and 
finally,  for  sodium  sulphate,  the  latter  being  most 
simply  determined  gravimetrically  by  precipitation 
with  barium  chloride.  The  crude  lyes  are  also  exam- 
ined for  the  same  substances,  and  at  times  also  for 
sodium  ferrocyanide,  by  oxidation  with  a  just  sufficient 
quantity  of  chlorinated-lime  solution  and  titration 
with  a  copper-sulphate  solution  empirically  standard- 
ized against  pure  potassium  ferrocyanide.  The  end- 
point  of  this  reaction  is  recognized  by  bringing  together 
a  drop  of  the  liquid  on  a  porcelain  surface  with  some 
dilute  solution  of  ferrous  sulphate,  the  color  chang- 
ing from  a  blue  to  a  reddish  when  the  copper  is  in 
excess.  In  the  carbonated  lyes  there  is  moreover  deter- 
mined the  carbonic  acid  of  the  bicarbonate,  and  most 
simply  by  adding  phenolphtalein,  cooling  to  nearly 
0°  C.,  and  titrating  with  hydrochloric  acid  until  the 
red  color  just  disappears.  The  number  of  cubic  centi- 
meters of  1/5-normal  hydrochloric  acid  used  up  we 


INORGANIC  CHEMICAL  MANUFACTURES.         63 

will  designate  as  a.  Now  add  methyl  orange  followed  by 
more  hydrochloric  acid,  until  the  liquid  becomes  red. 
The  cubic  centimeters  of  1/5-normal  acid  required  for 
this  we  will  term  b.  b—a  will  then  give  the  soda  pres- 
ent as  NaHC03;  2b  will  give  that  present  as  Na2C03; 
and  a  +  b  the  total  soda  present.  The  leach-residue  is 
chiefly  examined  for  "utilizable  "  soda  by  digesting  it 
with  ten  times  its  weight  of  warm  water,  treating  the 
clear  liquid  with  carbonic  acid  until  H2S  begins  to  be 
evolved,  then  concentrating  by  evaporation,  filtering 
off  the  CaC03,  and  titrating  the  filtrate  with  normal  acid 
and  methyl  orange. 

In  the  factory  control  of  the  ammonia-soda  process, 
the  rock  salt,  brine,  limestone,  coke,  etc.,  are  examined 
as  above;  in  addition,  however,  the  gas  liquor  is  exam- 
ined as  detailed  on  page  85.  The  sodium  chloride  in 
the  ammoniacal  brine  is  determined  as  on  page  60, 
and  the  ammonia  either  by  titration  or,  very  accurately, 
by  driving  it  over  into  normal  hydrochloric  acid  by 
boiling,  as  detailed  on  page  56.  The  bicarbonate  in 
crude  bicarbonate  is  estimated  as  on  page  62.  The 
lime-kiln  gases  are  examined  for  carbonic  acid  with  the 
gas-burette,  as  described  on  page  8. 

For  the  factory  control  of  the  manufacture  of  caustic 
soda,  the  examination  of  the  crude  caustic  lye  is  of  im- 
portance, in  addition  to  that  of  the  substances  already 
mentioned.  The  alkalimetric  titer  is  ascertained  by 
means  of  normal  hydrochloric  acid  and  methyl  orange; 
then  the  NaOH  and  the  Na2C03  are  determined  by  first 
ascertaining  the  number  of  cubic  centimeters  of  normal 


64  TECHNO-CHEMICAL  ANALYSIS. 

hydrochloric  acid  used  up  (and  at  a  low  temperature), 
employing  phenolphtalein  (this  we  will  term  a),  and 
then  determining  the  further  number  used  up,  using 
methyl  orange  (which  we  will  designate  as  6),  as  de- 
scribed on  pp.  62  and  63.  In  this  case  a  —  b  is  equiva- 
lent to  the  NaOH,  while  26  represents  the  Na2CO3. 
Lastly,  the  sulphide  is  determined  by  titrating  with 
iodine  solution,  as  described  on  page  62. 

The  lime  deposit  also  should  be  examined  as  to  its 
content  of  soda  compounds,  by  boiling  and  titrating. 

Electrolytic  alkali  lyes  are  examined  like  bleaching- 
liquors  (page  68). 

The  commercial  products  of  the  soda  industry  are 
as  follows: 

Calcined  Soda. — This  consists  essentially  of  anhy- 
drous sodium  carbonate,  the  content  (alkalimetric 
titer)  of  which  is  ascertained  by  igniting  2.65  grm.,  dis- 
solving, and  titrating  with  normal  hydrochloric  acid  and 
methyl  orange  in  the  cold.  Every  cubic  centimeter  of 
normal  acid  indicates  2  per  cent,  of  Na2C03.  The  Ger- 
man degrees  indicate  the  percentage  of  Na2C03 ;  the 
English,  the  percentage  of  Na20 ;  and  the  French,  as  the 
Descroizilles,  indicate  how  many  parts  of  H2S04  are 
neutralized  by  100  parts  of  the  soda.  Chemically  pure 
sodium  carbonate  would  indicate  100  German  degrees, 
58.5  English  degrees,*  or  92.45  degrees  Descroizilles. 

The  commercial  soda  is  moreover  tested  as  to  its  volu- 
metric weight,  technically,  by  transferring  5  or  6  sepa- 


*  In    actual    practice,    English    commercial   analysts   frequently 
state  the  number  by  J  to  1  degree  higher  than  here  given. 


INORGANIC  CHEMICAL  MANUFACTURES.          65 

rate  portions  of  the  anhydrous,  ground  soda  to  a  tared 
vessel  of  stout  glass,  ground  off  smooth  at  the  top,  and 
of  known  capacity,  the  powder  being  each  time  pounded 
down  and  the  excess  scraped  off,  the  quantity  remain- 
ing being  then  ascertained-  by  weighing  back.  By  this 
process  the  volume  which  100  cc.  of  the  ground  soda 
occupies  is  ascertained. 

A  complete  analysis  of  the  soda  is  rarely  necessary; 
it  comprises  the  determination  of  the  insoluble  matter 
present,  the  chlorides,  sulphate,  bicarbonate,  caustic 
soda,  and  sodium  sulphide,  so  far  as  these  are  present, 
but  it  never  happens  that  these  are  all  present  (com- 
pare page  62  et  seq.). 

Crystal  Soda  is  at  times  adulterated  with  large  quan- 
tities of  Glauber's  salt.  It  should  never  show  less  than 
34  per  cent,  of  Na2C03  by  titration. 

Caustic  Soda. — It  is  not  an  easy  matter  to  take  a 
sample  of  this,  because  the  substance  usually  occurs 
in  large  blocks,  from  having  been  poured  into  iron  drums 
while  fluid,  and  its  composition  varies  at  different  parts 
of  the  drum.  If  the  containers  in  which  it  is  kept  are 
not  absolutely  air-tight,  it  attracts  moisture  and  car- 
bonic acid  from  the  air,  so  that  a  false  crust  forms 
which  must  be  removed  by  scraping  before  the  quantity 
intended  for  analysis  is  weighed  off.  After  the  scraping 
has  been  done,  50  grm.  are  dissolved  in  sufficient  water 
to  make  1  liter,  and  the  total  alkali  titrated  in  50  cc. 
of  the  solution  (2.5  grm.  of  the  substance)  by  means  of 
normal  acid  and  methyl  orange.  In  another  50  or 
100  cc.  of  the  solution  the  sodium  carbonate  still  present 


66 


TECHNO-CHEMICAL  ANALYSIS 


is  determined,  and  for  most  purposes  with  sufficient 
accuracy  by  consecutive  titration  with  phenolphtalein 
and  methyl  orange  (page  63) ,  but  accurately,  by  the 
volumetric  determination  of  the  C02  according  to 
Lunge  and  Marchlewsky  (page  30). 

Bicarbonate  is  examined  by  the  above-mentioned 
methods  as  to  its  content  of  Na2C03  (compare  page  62) . 

CHLORINE  INDUSTRY. 

In  the  small  manufacturing  process,  as  well  as  in  the 
completion  of  the  Weldon  process,  manganese  dioxide 
is  used,  together  with  hydrochloric  acid,  for  effecting 
the  evolution  of  chlorine;  the  dioxide  is  tested  as  to 
its  actual  content  of  Mn02  as  follows: 

Weigh  off  1.0875  grm.  of  the  manganese  dioxide,  very 
finely  powdered  and  dried  by  heating  for  some  time  at 
100°  C.,  and  introduce  it  into  a 
flask,  which  is  then  closed  with  a 
Bunsen  rubber"  valve,  or  better 
yet,  with  a  Contat  apparatus,  as 
shown  in  fig.  14,  and  which  con- 
tains a  small  quantity  of  sodium- 
bicarbonate  solution.  To  the  man- 
ganese dioxide  add  75  cc.  of  a  solu- 
tion of  100  grm.  pure  ferrous  sul- 
phate and  100  cc.  of  pure  sul- 
phuric acid  in  1  liter  of  water;  the 
solution  must  be  standardized 
against  a  titrated  potassium-permanganate  solution 
the  same  day  it  is  used.  Then  close  the  flask,  and 


INORGANIC  CHEMICAL  MANUFACTURES.         67 

boil  until  the  manganese  dioxide  is  decomposed.  The 
Contat  apparatus  is  then  adjusted  in  order  that  the 
liquid  may  cool  without  the  possibility  of  any  air  com- 
ing into  contact  with  it;  when  cool,  the  liquid  is  titrated 
back  with  permanganate  solution,  and  the  volume  used 
up  deducted  from  the  volume  equivalent  to  the  75  cc. 
of  ferrous-sulphate  solution.  Every  cubic  centimeter 
of  1/2-normal  permanganate  solution  corresponds  to 
0.02715  grm.,  or  2  per  cent.,  Mn02. 

Limestone  is  used  in  the  production  of  caustic  lime 
for  manufacturing  chlorinated  lime,  and  in  the  regen- 
eration of  the  manganese  dioxide  in  the  Weldon  process. 
The  limestone  is  examined  either  by  determining  the 
CaO  or  the  C02.  The  former  is  effected  accurately 
enough  by  dissolving  1  grm.  in  25  cc.  normal  hydro- 
chloric acid  and  titrating  back  with  normal  soda. 
Every  cubic  centimeter  of  normal  acid  used  up  repre- 
sents 0.028  grm.  CaO,  or  0.05006  grm.  CaC03.  The 
carbonic  acid  is  determined  either  by  the  loss  in  weight 
in  a  weighable  apparatus  containing  the  quantity  of 
hydrochloric  acid  necessary  for  the  decomposition,  and 
provided  as  well  with  an  apparatus  for  drying  the  C02 
evolved;  or  more  accurately,  and  at  the  same  time 
more  rapidly,  by  the  volumetric  method  (page  30), 
which,  of  course,  assumes  that  the  proper  apparatus 
is  available. 

Caustic  lime  is  examined  for  free  CaO  by  slaking 
100  grm.  of  the  lime  with  enough  water  to  make  a  thin 
cream  (500  cc.),  100  cc.  of  which  are  diluted  with  water 
to  make  500  cc.,  shaking,  and  titrating  25  cc.  of  the 


68  TECHNO-CHEMICAL  ANALYSIS. 

mixture  (  =  1  grm.  caustic  lime)  with  phenolphtalein 
and  normal  hydrochloric  acid,  with  thorough  shaking, 
until  the  red  color  just  disappears.  Every  cubic  centi- 
meter of  normal  acid  is  equivalent  to  0.02806  CaO. 

The  chlorine  gas,  whether  obtained  by  the  Deacon 
process  or  electrolytically,  must  be  examined  for  car- 
bonic acid.  This  is  most  simply  effected  by  filling  two 
burettes  with  100  cc.  each  of  the  chlorine.  In  the  one, 
the  chlorine  is  absorbed  by  potassium  iodide,  and  the 
iodine  separated  estimated  with  arsenic  solution  or  thio- 
sulphate  solution;  every  cubic  centimeter  of  1/10-normal 
titrating  solution  indicates  0.003545  grm.  of  chlorine,  or 
1.1228  cc.  dry  chlorine  at  0°  C.  and  760  mm.;  the  re- 

760(273  +0 
duction  may  be  made  by  using  the  formula  -77 — AO~Q  , 

(0 —  I JA  Id 

t  being  the  prevailing  temperature  and  b  the  baro- 
metric pressure  (/  is  the  vapor-tension  at  t).  In  the 
second  burette  the  chlorine  and  the  C02  are  absorbed 
together  by  soda-lye,  and  the  C02  ascertained  by  dif- 
ference. 

Electrolytic  Lyes  and  Bleaching-fluids.  —  Bleaching- 
fluids  consist  of  mixtures  of  hypochlorites  and  chlorides, 
and  generally  also  a  little  chlorate,  hypochlorous  acid, 
and  at  times  alkali,  either  free  or  as  carbonate.  The 
electrolytic  lyes  contain  the  same  constituents,  but  in 
entirely  different  proportions;  in  these  lyes  the  caus- 
tic alkali  preponderates.  The  analytical  methods, 
however,  are  the  same  for  both  lyes. 

In  bleaching-fluids,  the  most  important  constituent 
to  be  determined  is  the  active  chlorine,  and  in  the  same 


INORGANIC  CHEMICAL  MANUFACTURES.         69 

manner  as  in  the  case  of  chlorinated  lime  (see  below). 
In  addition  it  may  be  also  required  to  determine  the 
free  hypochlorous  acid  present.  This  is  determined  by 
adding  potassium  iodide,  when  the  following  reactions 
take  place: 

1.  NaOCl+2KI+H20  =  NaCl+2KOH+I2. 

2.  HOC1 +2KI  =  KC1  +KOH  +I2. 

The  iodine  liberated  in  these  reactions  is  neutralized 
by  thiosulphate,  and  the  two  reactions  then  titri- 
metrically  differentiated  by  the  fact  that  in  reaction 
1  twice  as  much  KOH  is  liberated  as  in  reaction  2. 

Chlorates  are  determined  together  with  the  active 
chlorine  by  boiling  with  ferrous-sulphate  solution,  and 
titrating  back  with  permanganate  solution,  the  active 
chlorine  being  then  deducted  from  the  total. 

The  bases  are  determined  by  the  action  of  neutral 
hydrogen  peroxide  upon  the  active  chlorine,  as  in  the 
following  reaction :  NaOCl  +  H202  =  NaCl + H20 + 02. 
The  caustic  alkali  as  well  as  the  carbonate  is  then 
titrated  in  the  usual  way  with  hydrochloric  acid  and 
phenolphtalein  followed  by  methyl-  orange  (see  page 
63). 

Chlorinated  Lime. — The  ready  decomposability  of  this 
substance  must  be  taken  into  account  when  taking  the 
sample  and  preparing  it  for  analysis,  hence  the  opera- 
tions are  to  be  rapidly  conducted  and  the  substance 
exposed  as  little  as  possible  to  the  air. 

Chlorinated  lime  is  examined  only  as  to  its  content 
of  active  chlorine,  the  result  being  expressed  either  in 
per  cents,  by  weight,  or  (as  in  France)  in  Gay-Lussac 


70  TECHNO-CHEMWAL  ANALYSIS. 

degrees,  i.e.,  the  number  of  liters  of  chlorine  gas  at 
0°  C.  and  760  mm.  that  are  evolved  from  one  kilo  of 
chlorinated  lime.  One  weigh t-per  cent,  of  chlorine  is 
equivalent  to  3.15  degrees  Gay-Lussac;  or,  100°  G.-L. 
are  equivalent  to  31.78  per  cent,  of  chlorine. 

Of  the  many  chlorimetric  methods  that  of  Penot  is 
the  simplest  and  at  the  same  time  the  most  accurate. 
It  is  based  upon  the  oxidation  of  sodium  arsenite  to 
arsenate  by  the  chlorinated  lime,  and  the  recognition 
of  the  end  of  the  reaction  by  the  aid  of  potassium- 
iodide-starch  paper,  as  follows:  Weigh  off  7.091  grm. 
of  the  chlorinated  lime  to  be  examined,  triturate  it  in 
a  porcelain  mortar  with  a  little  water  to  form  a  thin 
cream,  dilute  with  more  water,  and  wash  the  whole 
into  a  liter  flask,  which  is  then  filled  to  the  mark.  For 
every  test  50  cc.  of  the  freshly  shaken  mixture,  corre- 
sponding to  0.3545  grm.  chlorinated  lime,  is  taken,  and 
into  it  is  run  from  a  burette  1/10-normal  arsenite  solu- 
tion (prepared  by  prolonged  boiling  of  4.95  grm.  pure 
arsenous  acid  with  10  grm.  sodium  bicarbonate  and 
200  cc.  water,  filtering,  and  making  up  to  one  liter). 
When  the  saturation-point  is  reached,  place  a  drop  of 
the  liquid  on  potassium-iodide-starch  paper;  a  blue 
color  will  develop  so  long  as  any  chlorinated  lime  is  still 
present.  The  non-formation  of  a  color  is  an  evidence 
of  the  end  of  the  reaction.  Every  cubic  centimeter  of 
the  arsenic  solution  is  equivalent  to  1  per  cent,  of 
active  chlorine. 


INORGANIC  CHEMICAL  MANUFACTURES.         71 

POTASSIUM  SALTS. 

The  raw  material  for  the  manufacture  of  these  is 
chiefly  the  Stassfurter  potassium  chloride,  which  occurs 
as  Carnallit,  Kainit,  etc.  .  In  examining  the  chloride,  dis- 
solve 100  grm.  in  sufficient  water  to  make  one  liter,  and 
in  the  clear  liquid  determine  the  sulphuric  acid  gravi- 
metrically  with  barium  chloride.  To  determine  the 
potassium,  precipitate  the  sulphuric  acid  in  100  cc.  of  the 
liquid  by  adding  just  sufficient  barium  chloride,  whereby 
all  the  alkalies  are  converted  into  chlorides,  then  evapo- 
rate one-tenth  of  the  nitrate  (equivalent  to  1  grm.  of 
substance)  to  dryness,  decompose  the  MgC02  by  ignit- 
ing with  oxalic  acid,  convert  the  CaO  into  CaC03  by 
means  of  ammonium  carbonate,  separate  the  alkali 
chlorides  from  the  earth-alkalies  by  dissolving,  filter- 
ing, and  again  evaporating,  weigh  the  purified  KC1+ 
NaCl,  and  determine  the  potassium  with  platinic  chlo- 
ride; the  NaCl  is  found  from  the  difference. 

The  potassium  determination  is  effected  with  a  pla- 
tinic-chloride  solution,  1  cc.  of  which  contains  1  grm. 
of  platinum.  Add  sufficient  of  this  solution  to  the 
solution  of  the  potassium  salt  (which  must  be  in  the 
form  of  chloride  and  as  pure  as  possible),  evaporate  in 
a  porcelain  dish  to  a  syrupy  consistency  on  the  water- 
bath,  stir  the  residue  with  20  cc.  strong  alcohol,  and 
decant  the  solution  through  a  filter  previously  dried  at 
120°-130°  C.  and  weighed;  repeat  the  stirring  with 
alcohol  and  decantation  two  or  three  times,  wash  the 
precipitate  onto  the  filter,  and  press  it  between  filter- 


72  TECHNO-CHEMICAL  ANALYSIS. 

paper,  then  dry  at  120°-130°  C.,  and  weigh  the  potas- 
sium-platinic  chloride,  of  which  1  part  is  equivalent  to 
0.3056  part  KC1  or  0.1928  part  K20. 

Commercial  potassium  chloride  is  similarly  examined, 
and  so  are  also  potassium  salts  with  high  sulphuric-acid 
content  (manurial  salts) ;  in  this  case,  however,  the  pre- 
cipitation of  the  sulphuric  acid  in  the  boiling,  strong 
hydrochloric-acid  solution  must  be  effected  by  adding 
the  barium-chloride  solution  drop  by  drop,  and  in  such 
a  manner  that  there  should  be  present  a  small  remainder 
of  sulphuric  acid  rather  than  an  excess  of  barium  chlo- 
ride. 

The  perchlorate  process  is  also  frequently  employed; 
in  it  the  sulphuric  acid  may  be  much  more  easily  re- 
moved, as  the  presence  of  an  excess  of  barium  chloride 
is  not  material.  Evaporate  the  filtrate  from  the  barium 
sulphate  on  the  water-bath  with  1J  times  the  quantity 
of  perchloric  acid  necessary  to  decompose  all  the  salts, 
and  until  the  odor  of  hydrochloric  acid  has  entirely 
disappeared,  allow  to  cool,  and  wash  the  residue  with 
96-per-cent  alcohol  to  which  0.2  per  cent,  of  perchloric 
acid  has  been  added.  Then  bring  the  precipitate  onto 
a  filter  as  in  the  platinum  method,  and  weigh  as  in  that 
method  (page  71). 

Potash. — In  the  manufacture  of  potash  by  the  Leblanc 
process  practically  the  same  methods  are  employed  as 
are  detailed  on  page  62  et  seq. ;  and  likewise  in  the  po- 
tassa  lyes  obtained  electrolytically,  as  on  page  68  et  seq. 

In  the  commercial  products  from  potash  and  caustic- 
potassa  lye,  the  potassa  content  must  be  determined  as 


INORGANIC  CHEMICAL  MANUFACTURES.         73 

well  as  the  alkalinity.  This  is  effected  just  as  in  the 
case  of  potassium  chloride  (page  71),  by  saturating 
with  hydrochloric  acid,  precipitating  the  sulphuric  acid 
with  barium  chloride,  and  treating  the  chlorides  formed 
with  platinum  chloride.  • 

In  vinasse-potash  there  must  also  be  determined  the 
phosphoric  acid  by  precipitating  the  nitric-acid  solution 
with  ammonium  molybdate,  dissolving  the  precipitate 
in  ammonia,  and  precipitating  with  magnesia  mixture 
in  the  usual  way. 

Potassium  Cyanide. — The  cyanogen  is  determined  by 
dissolving  0.5  grm.  of  the  substance  in  100  cc.  water, 
adding  5  cc.  normal  soda  lye  and  0.5  grm.  sodium  bi- 
carbonate, and  titrating  with  1/10-normal  silver  solu- 
tion so  long  as  the  resulting  precipitate  continues  to 
dissolve.  As  soon  as  opalescence  persists  the  reaction 
is  at  an  end.  One  cubic  centimeter  of  the  silver  solu- 
tion corresponds  to  0.01302  grm.  KCN. 

If  it  is  desired  to  determine  the  sodium  salt  which  is 
frequently  present  in  large  quantity  in  commercial 
products,  add  5  cc.  of  diluted  hydrochloric  acid  to 
0.5  grm.  of  the  substance,  cautiously  evaporate  on  the 
water-bath  (because  of  the  vapors  of  hydrocyanic  acid 
evolved),  weigh  the  chlorides  as  such,  and  in  them 
determine  the  KC1  as  on  page  71;  the  NaCl  is  then 
found  from  the  difference. 

Potassium-  or  Sodium-ferrocyanide  is  examined  by 
acidulating  the  solution  with  sulphuric  acid  and  titrat- 
ing with  potassium-permanganate  solution  until  per- 
manent redness.  For  every  part  of  iron,  as  indi- 


74  TECHNO-CHEMICAL  ANALYSIS. 

cated    by   the    permanganate,    calculate    7.543   parts 
K4Fe(NC)6. 

CLAY  AND  CEMENT  INDUSTRY. 

In  the  wider  sense  we  include  under  this  category 
the  investigation  of  the  clays  used  in  pottery,  as  well 
as  that  of  marls  and  cements. 

Clay  used  in  the  Manufacture  of  Bricks  and  Cera- 
mics.— This  is  examined  for  (a)  sandy  constituents 
(which  render  the  (clay  poor),  and  6)  for  carbonates  of 
calcium  and  magnesium.  The  former  are  determined, 
not  by  chemical  methods,  but  by  elutriating  a  finely 
triturated  portion  of  the  sample  with  water,  whereby 
the  clay  itself  is  retained  in  suspension,  while  the 
quartz  sand,  the  breccia,  calcium  carbonate,  etc.,  rap- 
idly subside.  The  carbonates,  however,  are  deter- 
mined just  as  in  the  case  of  limestone  (page  67). 

By  "rational  "  analysis  is  understood  the  separation 
of  the  aluminium  silicate  from  the  quartz  sand  and 
felspathic  residues,  etc.,  by  chemical  methods,  and 
which  is  accomplished  more  or  less  completely  by 
treatment  with  concentrated  sulphuric  acid,  or  by 
boiling  with  solutions  of  alkali  carbonates. 

In  the  case  of  refractory  materials  the  clay  must  be 
examined  as  to  its  fusibility,  by  what  is  called  the 
pyrometric  test.  Samples  of  the  substance  are  pre- 
pared, and  are  heated  in  a  suitable  oven,  in  which 
at  the  same  time  various  normal  clays  are  also  placed. 
For  the  latter  purpose  Seger  fusible  cones  are  usu- 
ally employed;  these  are  made  of  various  degrees  of 


INORGANIC  CHEMICAL  MANUFACTURES.          75 

fusibility,  and  are  variously  numbered,  the  num- 
bers indicating  the  temperature  at  which  the  samples 
just  begin  to  soften  or  fuse. 

Clay  and  marl  for  the  manufacture  of  cement  are, 
in  important  cases,  fully  examined  by  quantitative 
analytical  methods.  For  the  ordinary  manufactur- 
ing control  it  is  usually  sufficient  to  determine  the 
carbonic  acid,  by  means  of  the  calcimeter  described  on 
page  29,  or  more  accurately  by  aid  of  the  apparatus 
shown  on  page  66,  calculating  the  carbonic  acid  as 
CaC03  (44  parts  C02=100  parts  CaC03),  the  residue 
being  regarded  as  "clay." 

The  cements  are  examined,  if  at  all,  by  the  accurate 
methods  of  gravimetric  analysis.  More  important, 
however,  is  their  testing  by  a  number  of  mechanical 
and  other  practical  methods,  the  description  of  which 
can  not  here  be  gone  into.  Regarding  these  see  Chem.- 
Techn.  Untersuchungsmethoden,  I,  p.  645  et  seq. 

Aluminium  Preparations. — The  most  important  of 
these  is  the  aluminium  sulphate.  This  is  examined  in 
the  main  as  follows: 

1.  The  alumina,  content  is  determined  gravimetri- 
cally  by  precipitating  with  a  slight  excess  of  ammonia 
and  boiling  for  a  short  time;  or  volume trically  by 
adding  sodium  acetate  and  acetic  acid,  followed  by 
an  excess  of  sodium-phosphate  solution,  the  phosphoric 
acid  content  of  which  has  previously  been  ascertained 
by  titrating  with  uranium  solution  (see  below  under 
analysis  of  manures),  whereby  all  the  alumina  is  pre- 
cipitated as  phosphate,  and  then  titrating  back  the 


76  TECHNO-CHEMICAL  ANALYSIS. 

phosphate  not  used  up  by  employing  the  same  uranium 
solution. 

2.  Iron  should  be  present  only  in  small  traces  when 
the  preparation  is  intended  for  use  in  the  dyeing  indus- 
try. These  traces  can  not  be  determined  by  the  usual 
methods,  but  they  can  be  estimated  colorimetrically. 
For  this  purpose  a  solution  is  prepared  by  dissolving 
8.606  grm.  ferric  alum  in  1  liter  of  distilled  water 
and  diluting  this  solution  one-hundredfold,  so  that 
the  liter  will  contain  0.01  grm.  iron,  and  will  serve 
for  making  comparisons.  The  concentrated  solution 
remains  in  good  condition  for  a  very  long  time  if  5 
grm.  concentrated  sulphuric  acid  be  added,  and  the 
solution  is  kept  away  from  the  light;  the  diluted 
solution  keeps  only  a  few  days.  Now  dissolve  1  to  2 
grm.  of  aluminium  sulphate  in  a  small  quantity  of 
water,  heat  with  1  cc.  of  iron-free  nitric  acid,  cool, 
dilute  to  50  cc.  in  a  glass  cylinder  provided  with  a 
glass  stopper,  add  5  cc.  of  a  10-per-cent.  solution  of 
potassium  sulphocyanate,  followed  by  10  cc.  of  pure 
ether,  stopper  the  cylinder,  and  shake  thoroughly, 
whereby  the  ether  acquires  a  red  color.  In  quite  the 
same  manner  treat  the  solution  which  is  to  serve  for 
the  comparison,  and  which  is  prepared  by  diluting  a 
few  cubic  centimeters  of  iron  solution  of  known  strength 
to  50  cc.,  adding  5  cc.  of  sulphocyanate  solution  and  10 
cc.  of  ether,  and  shaking.  By  comparing  the  colors  on 
a  white  background  and  against  the  sky,  it  is  easy  to 
determine  from  the  depth  of  the  color  which  of  the 
solutions  used  for  ths  comparisons  corresponds  to 


INORGANIC  CHEMICAL  MANUFACTURES.         77 

aluminium-sulphate  solution,  and  to  thus  ascertain  the 
iron  content  of  the  latter.  The  comparison  is  best 
made  after  the  lapse  of  an  hour,  because  the  color  gradu- 
ally becomes  deeper. 

3.  Free  Acid. — Dissolve  1  to  2  grm.  of  the  aluminium 
sulphate  in  5  cc.  of  water,  add  5  cc.  of  a  cold  saturated 
solution  of  ammonium  sulphate,  stir  for  15  minutes,  and 
add  50  cc.  of  95-per-cent.  alcohol,  by  which  treatment 
the  aluminium  sulphate  is  precipitated  as  ammonium 
alum,  while  the  free  acid  remains  in  solution.  Then 
filter,  wash  the  contents  of  the  filter  with  50  cc.  alcohol, 
evaporate  the  alcohol  on  the  water-bath,  dilute  the 
residue  with  water,  and  titrate  with  1/10-normal  lye 
and  phenolphtalein. 

ARTIFICIAL  MANURES. 

To  these  belong  particularly  the  superphosphates,  to 
which  are  also  usually  added  ammonium  chloride,  and 
also  Chile  saltpeter  and  even  potassium  salts. 

The  superphosphates  are  chiefly  examined  for  the 
following : 

i.  Phosphoric  Acid. — To  determine  the  water-soluble 
phosphoric  acid,  shake  20  grm.  with  800  grm.  of  water, 
and  make  up  to  1  liter.  In  the  case  of  citrate-soluble 
phosphoric  acid  (in  Thomas  phosphate),  shake  5  grm.  in 
a  half -liter  flask  with  a  2-per-cent.  citric-acid  solution 
for  half  an  hour  in  an  agitation  apparatus.  For  the 
total  phosphoric  acid,  shake  10  grm.  of  the  substance 
with  25  cc.  of  water  or  with  5-per-cent.  sulphuric  acid, 
boil  with  50  cc,  of  concentrated  sulphuric  aci4 


78  TECHNO-CHEM1CAL  ANALYSIS. 

and  20  cc.  hydrochloric  acid,  with  frequent  shaking, 
for  one  hour;  on  cooling,  dilute  to  500  cc.,  and  filter. 
At  times  the  citrate-soluble  phosphoric  acid  is  also 
determined  as  follows:  Boil  5  grm.  of  the  super- 
phosphate with  150  cc.  of  a  solution  of  ammonium 
citrate  containing  5  per  cent,  of  10-per-cent.  ammonia 
for  one  hour  at  a  temperature  of  40°  C.,  and  then  dilute 
to  250  cc.  The  solution,  made  as  here  detailed,  is 
then  examined  by  volumetric  methods  where  rapid, 
but  not  very  accurate,  analyses  are  required;  for  more 
accurate  purposes,  the  methods  of  gravimetric  analysis 
are  employed. 

The  volumetric  analysis  is  effected  by  adding  50  cc. 
of  a  solution  of  ammonium  acetate  (containing  100  grm. 
of  ammonium  acetate  and  100  grm.  concentrated  acetic 
acid  per  liter)  to  200  cc.  of  the  solution  made  as  above 
(containing  20  grm.  per  liter),  whereby  the  iron  and 
alumina  are  precipitated  as  phosphates  (and  of  which 
half  the  weight  may  be  calculated  as  P205),  then  filter- 
ing, and  titrating  50  cc.  of  the  filtrate  (representing  40  cc. 
of  the  original  solution)  with  a  standardized  uranium- 
acetate  solution,  while  boiling,  until  a  drop  placed  on 
a  porcelain  plate  gives  a  brown  ring  on  contact  with 
a  drop  of  potassium-ferrocyanide  solution.  The  ura- 
nium solution  is  prepared  from  1  part  of  uranium  nitrate, 
28.2  parts  of  water,  and  0.1  part  of  ammonium  acetate, 
the  solution  being  standardized  against  calcium  phos- 
phate so  that  1  cc.  of  it  will  indicate  0.005  grm.  P205. 
This  method  is  now  employed  usually  only  in  the  case 
of  phosphates  free  from  iron  and  alumina. 


INORGANIC  CHEMICAL  MANUFACTURES  79 

The  gravimetric  analysis  is  effected  by  adding  concen- 
trated (75-per-cerit.)  ammonium-nitrate  solution,  and  a 
solution  of  150  grm.  of  ammonium  molybdate  in  1  liter 
of  water  plus  1  liter  of  nitric  acid  of  sp.  gr.  1.2.  The 
total  liquid  should  contain  not  less  than  15  per  cent,  of 
ammonium  nitrate,  and  not  less  than  50  cc.  of  molyb- 
denum solution  for  each  0.1  grm.  of  P205.  Heat  for 
10  minutes  to  80°  to  90°  C.,  allow  to  cool,  filter,  and 
wash  with  a  solution  of  150  grm.  of  ammonium  nitrate 
and  10  cc.  of  nitric  acid  per  liter.  Now  perforate 
the  point  of  the  filter,  and  wash  the  contents  into  a 
beaker  with  a  2^-per-cent.  ammonia  (using  75  cc. 
altogether  for  the  purpose),  add  for  each  0.1  grm.  P205 
drop  by  drop  10  cc.  of  magnesia  mixture  (55  grm.  crys- 
tallized MgCl2  and  70  grm.  NH4C1  per  liter  of  2^-per^ 
cent,  ammonia),  allow  to  stand  for  two  hours,  filter, 
wash  with  2^-per-cent.  ammonia,  dry,  burn  the  filter 
separately,  and  then  ignite  the  whole  in  a  platinum 
crucible,  finally  with  the  blast.  The  magnesium  pyro- 
phosphate  thus  found,  multiplied  by  0.6396,  gives  the 

P205. 

2.  Nitrogen. — (a)  Nitric-acid  nitrogen  is  determined 
by  Ulsch's,  Lunge's,  or  Schlosing-Grandeau's  method, 
as  detailed  on  pp.  56  and  57. 

(b)  Ammonia-nitrogen. — Distil  a  sample  (25  cc.  of  a 
solution  of  20  grm.  of  the  substance  dissolved  in  1  liter 
of  distilled  water,  and  diluted  to  150  cc.)  with  3  grm. 
of  calcined  magnesia  in  a  flask  provided  with  a  tube 
for  carrying  off  the  gas,  and  a  condenser,  until  100  cc. 
of  distillate  are  collected;  the  distillate  is  collected  in 


80  TECHNO-CHEM1CAL  ANALYSIS. 

standardized  acid  and  titrated  back  with  soda-lye.  Or, 
the  azotometer  described  on  page  27  may  be  employed. 

(c)  Total  Nitrogen  (including  of  course  organic  nitro- 
gen).— The  best  method  for  this  is  that  of  Kjeldahl  and 
Jodlbauer.  One  grm.  of  the  substance  is  placed  in  a 
Bohemian-glass  flask  of  350  cc.  capacity,  and  to  it  are 
added,  gradually  and  with  constant  shaking  and  cool- 
ing, 30  cc.  of  phenol-sulphuric  acid,  made  by  dissolving 
200  grm.  of  phosphoric  anhydride  in  500  cc.  of  concen- 
trated sulphuric  acid  and  mixing  this  with  a  solution  of 
40  grm.  of  phenol  in  500  cc.  of  concentrated  sulphuric 
acid.  After  one  hour  add,  very  gradually  and  with  con- 
stant and  vigorous  shaking,  2  to  3  grm.  of  dry  zinc-dust 
and  1  grm.  mercury,  heat  cautiously  to  boiling  after 
having  allowed  the  mixture  to  stand  for  an  hour  or  two, 
then  boil  vigorously  until  the  liquid  has  become  clear 
and  colorless  (which  may  require  from  ^  to  3  hours), 
allow  to  cool,  wash  with  200  cc.  of  water  into  a  500-cc. 
distillation  flask  provided  with  a  bulb  top  (page  56)  to 
prevent  any  liquid  being  spirted  over,  add  110  cc.  of 
nitrogen-free  soda  lye  of  sp.  gr.  1.285,  and  also  1  to  1.5 
grm.  zinc-dust,  and  distil  off  the  nitrogen  that  is  evolved. 
This  is  collected  in  a  receiver  containing  20  cc.  of  normal 
acid  and  connected  with  a  three-bulb  tube  (Peligot  or 
Will-Varrentrapp),  and  titrated  back  with  soda  lye  and 
methyl  orange.  A  small  condenser  is  interposed  be- 
tween the  flask  and  the  receiver. 

3.  Chlorates  and  Perchlorates  are  considered  as  in- 
jurious, and  are  determined,  usually  together,  as  on, 
page  57, 


INORGANIC  CHEMICAL  MANUFACTURES.         81 

4.  Potassium  is  determined  as  on  page  71. 

5.  Ferric  oxide  and  Alumina  must  be  determined  in 
the  crude  phosphates,  and  likewise  in  the  superphos- 
phates, in  order  to  be  able  to  judge  of  the  "  re  version" 
of  the  phosphate  to  the  insoluble  form.     Glaser's  method 
serves  as  a  standard  for  this  purpose;   it  is  as  follows: 
Dissolve  5  grm.  of  the  phosphate  in  25  cc.  of  nitric  acid 
of  sp.  gr.  1.2  and  12.5  cc.  of  hydrochloric  acid  of  sp.  gr. 
1.12,  make  up  to  500  cc.,  add  25  cc.  of  concentrated  sul- 
phuric acid  to  100  cc.  of  the  filtrate,  shake  for  five  min- 
utes, add  100  cc.  of  95-per-cent.  alcohol,  cool,  add  alcohol 
to  make  250  cc.,  shake  again,  filter  after  half  an  hour, 
evaporate  100  cc.  of  the  filtrate  until  the  alcohol  has 
been  driven  off,  then  add  50  cc.  water,  boil,  add  am- 
monia until  the  reaction  is  alkaline,  boil  off  the  excess 
of  ammonia,  allow  to  cool,  and  filter  off  the  precipitate 
of  ferrous  and  aluminium  phosphates,  which  then  wash 
with  warm  water  and  ignite.     Half  of  the  weight  is 
assumed  to  be  Fe20a  +A1203. 

If  it  is  desired  to  determine  the  individual  contents 
of  iron  and  alumina,  estimate  the  iron  in  a  separately 
made  hydrochloric-acid  solution,  after  reducing  with 
zinc  and  adding  manganese  sulphate,  by  titrating  with 
potassium  permanganate.  The  alumina  is  found  from 
the  difference. 

6.  Lime  is  chiefly  determined  in  Thomas  phosphates, 
and  in  fact  by  precipitating  a  concentrated  hydrochloric- 
acid  solution  with  ammonia  and  neutral  ammonium 
oxalate;  the  precipitate  is  washed  with  water,  dissolved 
in  a  little  hydrochloric  acid,  and  precipitated  by  thq 


82  TECHNO-CHEMICAL  ANALYSIS. 

addition  of  a  mixture  of  10  cc.  sulphuric  acid  (1  :  3)  and 
150  cc.  of  96-per-cent.  alcohol;  the  calcium  sulphate  is 
washed  with  alcohol  and  weighed  as  CaS04. 

GAS  AND  AMMONIA  MANUFACTURE. 

Illuminating-gas.  —  The  technical  investigation  of 
this  gas  is  effected  by  the  methods  already  described 
on  page  7  et  seq.  The  more  accurate  investigation 
must  be  accomplished  by  means  of  apparatus  in  which 
mercury  is  used  as  the  confining  liquid,  e.g.,  the  Dreh- 
schmidt  apparatus,  the  description  of  which  would  be 
out  of  place  here.  It  is  proper,  however,  to  here  call 
attention  to  certain  useful  or  injurious  constituents  of 
illuminating-gas,  which  are  present  in  very  small  quan- 
tities, and  which  must  hence  be  determined  by  special 
methods. 

a.  Eihylene  and  benzol  are  most  simply  determined, 
according  to  Haber,  by  absorbing  both  the  gases  by 
standardized  bromine-water  in  a  Bunte  burette  (page 
9),  and  measuring  the  reduction  in  volume.     A  stand- 
ardized iodine   solution  is  then  allowed  to  enter  the 
tube,  whereby  a  quantity  of  iodine  equivalent  to  the 
excess  of  bromine  present  is  liberated,  this  being  then 
volumetrically    determined    by    thiosulphate    solution^ 
and  the  ethylene  calculated  according  to  the  formula: 
1  cc.  decinormal  iodine  solution  is  equivalent  to  1.1195 
cc.  C2H4  at  0°C.  and  760  mm.    The  benzol  is  found 
from  the  difference. 

b.  Carbonic  acid  is  determined  by  passing  a  measured 
volume  of  the  gas  through  a  baryta  solution  of  known 


INORGANIC  CHEMICAL  MANUFACTURES.         83 

strength,  and  titrating  back  with  oxalic-acid  solution; 
or  by  means  of  the  Rudorff  apparatus,  which  con- 
sists of  a  three-necked  flask  of  about  1  liter  capacity, 
in  one  neck  of  which  a  burette  is  ground  to  fit  accu- 
rately; from  this  burette  potassa  lye  is  allowed  to 
flow  so  long  as  it  is  saturated  by  the  carbonic  acid; 
the  volume  of  potassa  lye  used  up  is  read  off  on  the 
burette,  and  corresponds  to  the  C02.  A  manometer 
inserted  in  another  neck  serves  to  keep  the  pressure 
before  and  after  the  operation  uniform. 

c.  Hydrogen  sulphide  is  determined  in  a  Bunte  bu- 
rette by  means  of  an  iodine  solution  containing  1.134 
grm.  I  per  liter;  1  cc.  of  this  solution  indicates  0.1  cc. 
of  H2S.    The  solution  is  allowed  to  rise  hi  the  burette, 
while  being  shaken,  until  a  slight  excess  is  present,  which 
is  recognized  by  the  yellow  color  the  liquid  assumes  (due 
to  the  milkiness  caused  by  the  precipitated  sulphur). 
As   the   confining  water  has   previously  been   drawn 
down  to  the  lower  mark   (—10),  the  volume  of  the 
iodine  solution  used  up  may  be  directly  read  off  on 
the  burette,  and  from  it  the  volume  of  H2S  calculated. 
In  accurate  determinations,  however,  the  gas  in  the 
burette,  the  volume  of  which  was  originally  100  cc., 
must,  after  noting  the  temperature  and  pressure,  be 
reduced  to  0°  C.  and  760  mm.  and  dryness. 

d.  The    total   sulphur   is    determined    in    the    Dreh- 
schmidt  apparatus.     A  volume  of  gas  accurately  meas- 
ured by  passing  through  a  gas-meter  is  burned  by  the 
aid  of  a  current  of  air  which  has  been  purified  by  pass- 
age  through  pumice-stone  impregnated  with  potassa 


84  TECHNO-CHEMICAL  ANALYSIS. 

lye,  the  burning  being  done  in  a  Bunsen  burner  above 
which  a  glass  cylinder  is  fixed.  The  combustion  prod- 
ucts are  drawn  by  the  aid  of  a  water-pump  through 
three  absorption-flasks  containing  potassium-carbonate 
solution  and  a  little  bromine-water,  and  the  sulphuric 
acid  formed  is  determined  with  barium  chloride. 

e.  Ammonia   is    determined   as    in   Reich's   method 

• 

(page  23),  by  drawing  the  gas  by  means  of  an  aspira- 
tor or  gas-meter  through  a  standardized  sulphuric  acid 
tinted  with  an  indicator,  until  the  change  of  color 
shows  that  the  acid  has  been  saturated.  The  acid 
corresponds  to  its  equivalent  of  ammonia,  e.g.,  1  cc.  of 
decinormal  acid  corresponds  to  0.0017  grm.  NH3. 

/.  The  candle-power  is  ascertained  by  physical  means, 
using  a  photometer,  regarding  the  details  of  which  see 
Chem.-Techn.  Untersuchungsmethoden,  II,  p.  634;  and 
also  respecting  the  specific  gravity,  II,  p.  649.  As  to 
the  determination  of  the  heat  values,  see  above,  page  38. 

Gas-purifying  Compound. — It  is  important  to  exam- 
ine the  compound  used,  for  the  following  particularly : 

a.  Sulphur. — Extract   the   compound   in   a   Soxhlet 
apparatus  with  pure  carbon  disulphide,  distil  off  the 
solvent,  and  weigh  the  residual  sulphur.    This  is,  of 
course,  still  impure,  containing  some   tar;    the   latter 
may  be  removed  by  washing  with  a  little  ether,  or  else 
by  oxidizing  the  sulphur  to  sulphuric  acid  by  means  of 
nitric  acid,  either  alone  or  with  the  addition  of  some 
potassium    chlorate,    and    then    determining    the   sul- 
phuric acid  formed  by  the  gravimetric  method. 

b.  Cyanogen  Compounds. — According  to  Drehschmidt, 


INORGANIC  CHEMICAL  MANUFACTURES.         85 

introduce  10  grm.  of  the  compound  into  a  half-liter  flask, 
add  150  grm.  of  water,  1  grm.  ammonium  sulphate, 
and  15  grm.  mercuric  oxide,  boil  for  15  minutes,  add 
J  to  1  cc.  of  a  saturated  solution  of  mercurous  nitrate 
and  ammonia  until  a  precipitate  no  longer  forms, 
then  fill  up  to  the  mark,  and  add  a  further  8  cc.  of 
water,  corresponding  to  the  volume  of  the  solid  sub- 
stance. Pass  through  a  dry  filter,  and  to  200  cc.  of  the 
filtrate  (=4  grm.  of  substance)  add  6  cc.  of  ammonia 
of  sp.  gr.  0.91,  and  7  grm.  of  zinc-dust  with  2  cc.  of 
potassa  lye  (30-per  cent.),  make  up  to  400  cc.,  and 
pass  through  a  dry  filter.  One  hundred  cc.  of  the  filtrate 
are  then  mixed  with  30  to  35  cc.  of  decinormal  silver 
solution  and  acidulated  with  diluted  nitric  acid  in 
order  to  precipitate  all  the  cyanogen  as  silver  cyanide. 
Now  make  up  with  water  to  400  cc.,  and  titrate  back 
200  cc.  of  the  clear  liquid  by  Volhard's  method  with 
ammonium  sulphocyanate  in  order  to  ascertain  the 
unused  excess  of  silver  solution.  Every  cubic  centi- 
meter of  the  decinormal  silver  solution  used  up  corre- 
sponds to  0.002598  grm.  of  cyanogen,  or  to  0.004771  grm. 
Prussian  blue. 

c.  Ammonia  is  determined  by  leaching  with  water, 
distilling  the  solution  with  caustic  lye  or  magnesia, 
and  collecting  the  distillate  in  standardized  acid,  as  on 
page  80. 

Gas  Liquor. — For  the  factory  control  this  is  frequently 
examined  only  with  the  areometer,  the  indications  of 
which,  in  this  case,  however,  are  very  uncertain  be- 
cause of  the  varying  composition  of  the  solutions. 


86 


TECHNO-CHEMICAL  ANALYSIS. 


The  examination  should  therefore  always  be  made  by 
the  following  chemical  methods: 

a.  Free  ammonia,  and  ammonia  combined  with  weak 
acids  (CO 2,  HS2).    This  is  also  designated  as  "volatile  " 
ammonia,  because  it  may  be  driven  off  from  the  gas  liquor 
by  simple  distillation,  and  without  any  addition  of  alkali. 
It  may  be  titrated  directly  with  normal  acid  and  methyl 
orange,  when  1  cc.  of  normal  acid  indicates  0.017  grm. 
NH3. 

b.  The  total  ammonia  is  best  determined  by  distilling 
with  caustic  soda  or  magnesia,  and  collecting  the  dis- 
tillate in  standardized  acid,  as  detailed  on  page  80. 

Ammonia  Liquor  is  examined  as  to  its  content  of  NH3 
usually  only  by  taking  the  specific  gravity,  for  which 
purpose  the  folio  whig  table,  calculated  for  15°  C., 
serves: 


Specific 
Grav- 

Per 

Cent. 

Specific 
Grav- 

Per 

Cent. 

Specific 
Grav- 

Per 

Cent. 

Specific 
Grav- 

Per 

Cent. 

ity. 

NH3. 

ity. 

NH3 

ity. 

NH3. 

ity. 

NH3. 

0.998 

0.45 

0.966 

8.33 

0.934 

17.42 

0.902 

27.65 

0.994 

1.37 

0.962 

9.35 

0.930 

18.64 

0.898 

29.01 

0.990 

2.31 

0.958 

10.47 

0.926 

19.87 

0.894 

30.37 

0.986 

3.30 

0.954 

11.60 

0.922 

21.12 

0.890 

31.75 

0.982 

4.30 

0.950 

12.74 

0.918 

22.39 

0.888 

32.50 

0.978 

5.30 

0.946 

13.88 

0.914 

23.68 

0.886 

33.25 

0.974 

6.30 

0.942 

15.04 

0.910 

24.99 

0.884 

34.10 

0.970 

7.31 

0.938 

16.22 

0.906 

26.31 

0.882 

34.95 

The  ammonia  which  is  sold  as  "pure  "  is  usually 
qualitatively  examined  for  iron,  copper,  lime,  chlorides, 
and  also  empyreumatic  constituents  (pyridine  bases), 
for  the  last  usually  by  immersing  a  piece  of  filter-paper 
in  the  liquid,  and,  after  the  ammonia  has  evaporated 


"*«?>>» 


INORGANIC  CHEMICAL  MANUFACTUWS 

from  it,  observing  the  tarry  odor  which  then 
venes ;  or  by  observing  the  odor  which  likewise  develops 
after  neutralizing  with  sulphuric  acid. 

Ammonium  Sulphate  is  examined  by  distillation  with 
caustic  lye  (page  85),  or  by  the  azotometer  (page  27). 

ADDENDUM. 

Calcium  Carbide. — As  in  sampling  this  it  is  very  diffi- 
cult to  obtain  a  uniform  sample,  it  is  necessary  to  take 
at  least  50  grm.,  or  better  yet,  100  grm.,  for  analysis. 

Ordinarily  only  the  yield  of  gas  is  determined, 
although  the  gas  is  not  pure  acetylene.  The  volume  of 
gas  may  be  ascertained  by  direct  measurement,  for 
which  purpose  Lunge  and  others  have  devised  appa- 
ratus (see  Chem.-Techn.  Untersuchungsmethoden,  II, 
page  700),  or  it  may  be  determined  indirectly,  although 
less  accurately,  by  the  loss  in  weight  of  an  apparatus 
arranged  so  as  to  deliver  water  from  a  funnel  provided 
with  a  stopcock,  the  cock  being  opened  and  the  water 
allowed  to  fall  on  the  carbide,  the  evolved  gas  being 
dried  by  calcium  chloride.  0.4062  grm.  loss  in  weight 
corresponds  to  1  grm.  CaC2,  and  each  per  cent,  of  CaC2 
is  equivalent  to  34.89  liters  of  C2H2  at  0°  C.  and  760  mm. 

COAL-TAR  INDUSTRY. 

Coal-tar  itself  is  examined  only  as  to  its  specific 
gravity.  Before  ascertaining  this,  however,  it  is 
necessary  to  free  the  tar  from  water  by  allowing  it  to 
stand  for  twenty-four  hours  in  a  narrow-necked  bottle 
standing  in  water  at  50°  C.,  and  then  removing  the 


88  TECHNO-CHEMICAL  ANALYSIS. 

water,  which  separates  by  pouring  off  and  absorbing 
with  blotting-paper.  The  tar  is  then  allowed  to  cool 
to  15°  C.  An  araeometer  or  picnometer  can  not  be 
used  to  take  the  specific  gravity  of  the  viscid  tar.  It  is 
best  to  employ  a  cylindrical  weighing-tube  of  50  cc. 
capacity,  with  a  longitudinal  groove  filed  in  its  glass 
stopper.  The  specific  gravity  is  determined:  (a)  by 
first  weighing  the  dry  tube,  then  (6)  weighing  it  filled 
with  water,  then,  after  drying  the  tube  again,  filling 
it  two-thirds  full  with  tar,  placing  it  for  an  hour  in  hot 
water  until  all  the  air-bubbles  have  been  expelled,  allow- 
ing to  cool,  and  then  weighing  back  (c).  Now  fill  up 
with  water,  insert  the  stopper,  remove  the  water  which 
is  expelled  from  the  vessel,  allow  to  stand  in  a  large 
vessel  of  water  at  15°  C.,  and  then  weigh  again  (d). 
The  specific  gravity  sought  is  calculated  from  the  follow- 
ing formula: 

c—a 


b+c-(a+d)' 

The  free  carbon  is  sometimes  determined  by  exhaust- 
ing 10  grm.  of  the  tar  with  25  cc.  of  glacial  acetic  acid 
and  25  grm.  toluol,  filtering  through  a  weighed  filter, 
washing  with  toluol,  and  drying  at  120°  C. 

To  ascertain  the  yield  of  products  afforded  by  tar, 
large  quantities  must  be  submitted  to  distillation,  which 
is  a  matter  of  considerable  inconvenience  in  a  technical 
laboratory. 

Commercial  benzol  is  a  mixture  of  benzol,  toluol,  and 
the  higher  homologues  of  these  substances.  It  is  first 


COAL-TAR.  89 

examined  by  fractionally  distilling  100  cc.  in  a  frac- 
tionation-flask  provided  with  a  side-tube  and  a  ther- 
mometer-vessel arranged  so  as  to  be  surrounded  by  the 
vapor,  the  distillation  being  so  regulated  that  two  drops 
of  liquid  pass  over  per -second.  The  distillate  is  col- 
lected in  a  graduated  cylinder,  on  which  the  volume- 
per  cent,  may  be  read  off.  At  certain  fixed  points, 
which  vary  according  to  the  commercial  article,  the 
flame  is  removed,  and  the  distillate  present  in  the  con- 
denser allowed  to  run  for  two  minutes  before  reading  off. 
The  fixed  points,  in  the  case  of  the  light  benzols,  are 
80°,  90°,  100°,  and  110°  C.;  for  the  heavy  benzols  they 
are  110°,  120°,  and  130°  C.,  and  higher,  according  to 
agreement. 

In  the  trade  in  English  benzols  the  irrational  English 
test  is  still  employed,  in  which,  while  all  the  dimensions 
of  the  apparatus  are  accurately  prescribed,  the  ther- 
mometer-vessel is  not  surrounded  by  vapor,  but  is  im- 
mersed in  and  reaches  nearly  to  the  bottom  of  the 
liquid. 

Occasionally  there  are  also  determined:  (a)  Non- 
nitratable  constituents,  by  treatment  with  a  mixture  of 
strong  sulphuric  and  nitric  acids,  washing,  and  distil- 
ling off  the  non-nitrated  substances  by  passing-in  a  cur- 
rent of  steam. 

(6)  Carbon  disulphidcj  by  shaking  with  a  few  drops 
of  phenylhydrazine,  whereby  a  precipitate  of  phenyl- 
hydrazine  phenylsulphocarbaminate  forms  after  an 
hour. 

(c)  Thiophen. — On  shaking  with  a  solution  of  sodium 


00  TECHNO-CHEMICAL  ANALYSIS. 

nitrate  in  sulphuric  acid,  a  green  color,  changing  to  a 
blue,  develops  if  thiophen  is  present. 

Differentiation  of  Coal-tar  Benzol  from  Petroleum, 
Benzin,  Brown-coal  Oils,  etc. — This  is  already  quite 
easily  effected  by  the  odor  alone;  also  by  means  of  the 
specific  gravity,  which  in  the  case  of  the  coal-tar  prod- 
uct is  never  below  0.875,  while  with  the  others  it  is 
rarely  above  0.7.  Nitrosulphuric  acid  is  capable  of 
nitrating  the  former,  but  not  the  latter.  Picric  acid 
colors  benzol  yellow,  but  is  insoluble  in  petroleum 
benzin.  Coal-tar  pitch,  which  has  first  been  exhausted 
with  a  high-boiling  petroleum  and  then  dried,  colors 
benzol  a  deep  yellow,  but  petroleum  benzin  scarcely  at 
all,  a  fact  that  permits  an  approximately  quantitative 
valuation  of  a  mixture  of  the  two  to  be  made. 

Naphtalin  is  tested  as  to  its  melting-point  (79°  C.) 
and  boiling-point  (218°  C.).  It  should  have  a  pure 
white  color,  and  afford  a  colorless  solution  with  petro- 
leum benzin.  On  being  dissolved  in  pure,  concentrated 
sulphuric  acid,  it  should  not  impart  more  than  a  faint 
pink  color  to  the  acid.  A  sample  placed  under  a  glass 
bell  over  pure,  concentrated  nitric  acid  should  remain 
colorless  for  one  to  two  hours. 

Anthracene  is  always  examined  quantitatively  as  to 
the  quantity  of  anthraquinone  that  may  be  obtained 
from  it.  The  commercial  anthracene  is  boiled  with 
glacial  acetic  acid  and  chromic  acid,. the  anthraquinone 
then  precipitated  with  water,  thoroughly  washed, 
dried  at  100°  C.,  heated  with  fuming  sulphuric  acid  of 
68°  Be.  to  112°  C.,  diluted  with  water,  the  purified 


CARBOLIC  ACID.  91 

anthraquinone  filtered  off,  washed,  dried  at  100°  C., 
and  weighed.  It  is  then  strongly  heated  until  all  the 
anthraquinone  has  been  driven  off,  and  weighed  back. 
The  difference  multiplied  by  0.8558  gives  the  actual 
amount  of  anthracene  in  the  sample  examined.  In 
order,  however,  to  obtain  correct  results,  it  is  necessary 
to  observe  certain  definite  rules  in  carrying  out  the 
process  (comp.  Chem.-Techn.  Untersuchungsmetho- 
den,  II,  p.  740). 

Carbolic  Acid. — The  technical,  solid  carbolic  acid  is 
occasionally  pure,  or  almost  pure,  phenol,  but  it  fre- 
quently contains  higher  homologues  (cresols);  where 
a  considerable  quantity  of  these  are  present,  it  is  liquid. 
Perfectly  pure  phenol  melts  at  42°  C.,  while  technically 
pure  carbolic  acid  melts  at  35°  to  38°  C.,  and  dissolves 
in  20  paTts  of  water.  The  phenol  content  is  occasion- 
ally determined  gravimetrically  by  precipitating  the 
phenol  as  tribromphenol,  but  more  generally  indi- 
rectly by  volumetric  methods,  by  the  action  of  bro- 
minized  soda  solution  of  known  effective  value  on  the 
phenol,  and  then  titrating  back  the  excess  of  unused 
bromine.  For  this  purpose  there  is  used  a  mixture  of 
5NaBr+ NaBrOa,  obtained  by  dissolving  an  excess  of 
bromine  in  caustic  lye,  evaporating  to  dryness,  dis- 
solving about  9  grm.  of  the  residue  in  100  cc.  of  water, 
and  then  adding  concentrated  hydrochloric  acid  and 
potassium  iodide  to  the  solution;  the  iodine  that  has 
separated  out  is  then  titrated  back  with  thiosulphate. 
If,  now,  a  phenol  solution  is  treated  with  bromine  solu- 
tion and  hydrochloric  acid,  followed  by  potassium 


92  TECHNO-CHEMICAL  ANALYSIS. 

iodide,  the  slightest  liberation  of  iodine  indicates  the 
presence  of  phenol. 

Crude  Carbolic  Acid  and  Carbolic-acid  Preparations 
(creolin,  lysol,  sapocarbol,  etc.). — Crude  carbolic  acid 
is  tested  as  to  its  content  of  phenols  of  every  kind  by 
shaking  1  volume  with  9  volumes  of  caustic  lye  of 
sp.  gr.  1.079,  and  determining  the  volume  of  undis- 
solved  oils,  i.e.,  non-phenols. 

The  various  (saponaceous)  carbolic-acid  preparations 
are  similarly  shaken  with  caustic-soda  lye,  the  solution 
freed  from  hydrocarbons  by  shaking  out  with  ether, 
the  ether  then  driven  off,  the  solution  neutralized  with 
hydrochloric  acid,  and  the  fatty  acids  precipitated  as 
barium  salts  by  adding  barium  chloride  and  baryta- 
water.  The  acids  may  be  liberated  from  the  precipi- 
tate by  hydrochloric  acid,  and  then  determined.  The 
solution  freed  from  the  fatty  acids  is  acidulated,  and 
the  cresols  shaken  out  with  ether  and  weighed. 

Coal-tar  pitch  is  examined  as  to  its  softening-  and 
melting-points,  but  often  only  by  the  mastication  test. 
Soft  pitch  may  be  easily  pressed  out  flat;  medium- 
hard  pitch  will  only  receive  the  pressure  of  the  teeth; 
while  hard  pitch  crumbles  between  the  teeth  and  falls 
to  powder. 

For  more  accurate  examination  the  apparatus  of 
Kraemer  and  Sarnow  is  employed.  Twenty-five 
grammes  of  the  pitch  are  melted  in  an  iron  pan  in  an 
oil-bath  at  150°  C.;  the  pitch  should  form  a  layer  of 
about  10  mm.  in  the  pan.  Into  it  one  end  of  a  glass  tube 
of  5  to  7  mm.  internal  diameter,  and  open  at  both  ends, 


MINERAL  OILS.  93 

is  dipped,  the  upper  end  closed  with  the  finger,  the  tube 
removed,  and  the  pitch  allowed  to  solidify,  after  which 
that  adhering  to  the  glass  removed.  There  remains  a 
column  of  about  5  mm.  in  height  in  the  tube.  Now 
pour  about  5  grm.  of  mercury  into  the  tube,  and  hang 
the  latter  beside  a  thermometer  in  a  beaker  that  serves 
as  a  water-bath,  and  which  is  contained  within  a  simi- 
lar exterior  water-bath.  Heat  gradually  until  the 
mercury  penetrates  the  pitch,  and  note  the  tempera- 
ture; this  will  be  the  softening-point  of  the  pitch.  In 
the  case  of  soft  pitch  this  point  will  lie  between  50° 
and  51°  G.;  for  medium-hard,  between  60°  and  70°  C,; 
and  for  hard  pitch,  between  80°  and  89°  C. 

MINERAL  OILS. 

Petroleum. — In  order  to  determine  the  value  of 
petroleum,  the  latter  must  be  investigated  as  fully  as 
possible  as  to  various  constituents  obtainable  from  it, 
and  best  -by  the  fractional  distillation  of  as  conveniently 
large  a  quantity  as  possible,  duplicating  the  manu- 
facturing operations  on  a  small  scale.  We  will  here 
consider  only  the  investigation  of  the  commercial  prod- 
ucts obtained  from  petroleum. 

Benzin  is  the  name  applied  to  the  portion  of  crude 
petroleum  boiling  below  150°  C.  Of  this,  the  specific 
gravity  is  always  determined,  and  almost  always  by 
means  of  the  areometer.  Furthermore,  it  is  subjected 
to  a  fractional  distillation.  For  this  purpose  the  cus- 
toms-office employs  apparatus  made  entirely  of  metal, 
and  of  certain  dimensions.  The  chemist  generally 


94 


TECHNO-CHEMICAL   ANALYSIS 


makes  use  of  the  Engler  apparatus  (fig.  15) ,  the 
dimensions  of  which  are  here  accurately  given.  In- 
stead of  using  the  copper  side-tube,  the  vertical  cooler, 
and  the  glass  burette,  it  is  better  to  conduct  the 
distillation  at  a  temperature  below  200°  C.,  employing 


FIG.  15 

an  ordinary  Liebig  condenser,  just  as  in  the  case  of 
benzol,  page  88. 

Kerosene  is  similarly  examined  as  to  its  specific  grav- 
ity, and  also  ,by  the  distillation  test;  the  greater  part 
should  distill  over  between  150°  and  300°  C.  In  addition, 
the  clearness  and  color  must  be  observed,  and  above 
all  the  flash-point,  which  is  determined  for  the  pur- 
pose of  ascertaining  the  inflammability.  For  this  pur- 
pose there  is  generally  used  the  Abel  petroleum  tester, 
consisting  of  a  metallic  water-bath  in  which  is  suspended 


MINERAL  OILS. 


95 


a  smaller  metallic  vessel  for  the  reception  of  the  petro- 
leum. The  inner  vessel  is  closed  by  a  cover  which 
carries  a  thermometer  dipping  into  the  kerosene,  and 
an  ignition  apparatus  operated  by  a  small  train  of 
gear-wheels.  The  ignition  apparatus  consists  of  a 
small  slide  connected  with  a  small  lamp  which  is 
brought  into  contact  with  the  mixture  of  air  and 
kerosene  vapor  in  the  upper  part  of  the  vessel  when 
the  slide  is  moved.  The  temperature  at  which  the 
gaseous  mixture  ignites  is  noted,  and  corrected  for  the 
barometric  pressure  by  aid  of  a  table  which  accom- 
panies the  apparatus. 

At  times  the  sulphur  content  is  determined,  and  just 
in  the  same  manner  as  in  the  case  of  illuminating-gas 
(page  83  et  seq.)',  the  candle-power  is  also  determined 
by  photometric  methods. 

Lubricating-oils  are  chiefly  examined  as  to  their  vis- 
cosity by  means  of  the  Engler  viscosometer  (fig.  16). 
The  principle  upon  which  this 
apparatus  is  based  is  the  meas- 
urement of  the  rapidity  of 
flow  of  the  liquid  under  cer- 
tain definite  conditions.  The 
vessel  A  holds  about  240 
cc.  of  oil  when  filled  up  to 
the  mark.  The  outflow-tube 
through  which  the  liquid  flows, 

a,  is  20  mm.  long  and  2.8  mm. 

,          ,    .  FIG.  16. 

in    diameter;     before    being 

filled  it  is  closed  by  a  wooden  rod,  6.    The  mantle,  B; 


96  TECHNO-CHEMICAL  ANALYSIS. 

serves  as  a  water-  or  oil-bath,  and  is  heated  by  the  ring- 
burner,  d.  The  measuring-flask  C  bears  two  marks,  one 
indicating  200  cc.  and  the  other  240  cc.  For  the  degree 
of  fluidity  there  is  taken  the  quotient  obtained  by  divid- 
ing the  time  of  outflow  of  200  cc.  of  the  oil  (at  the  ex- 
perimental temperature)  by  the  time  of  outflow  of  200 
cc.  of  water  at  20°  C.  With  the  apparatus  at  normal 
conditions,  the  time  required  for  water  will  be  from  52 
to  54  seconds,  but  for  oils  it  will  naturally  be  more. 
The  temperature  of  the  oil  must  be  regulated  accord- 
ing to  the  requirements  of  the  case,  and  must  always 
be  stated  in  giving  the  results.  For  machine  and  gear- 
wheel oils  the  temperature  must  be  maintained  at  20° 
to  50°  C.;  for  cylinder-oils,  at  50°,  100°,  or  180°  C.,  and 
at  times  even  much  higher.  There  are  also  often  de- 
termined the  solidify  ing-point,  the  rate  of  flow,  and  par- 
ticularly the  flash-point,  for  which  Pensky  and  Martin 
have  constructed  a  special  apparatus,  differing  only 
from  that  of  Abel  (page  94)  by  the  addition  of  a  stir- 
ring arrangement. 

An  important  test  is  that  for  the  determination  of 
the  content  of  acid,  which  in  the  case  of  dark  mineral 
oils  may  amount  to  0.3  per  cent,  and  even  0.5  per  cent, 
(calculated  as  S03).  It  is  calculated  as  S03,  although 
it  consists  chiefly  of  phenols  and  resin  acids.  It  is 
determined  by  dissolving  10  cc.  of  the  oil  in  150  cc.  of 
a  mixture  of  4  parts  of  alcohol  and  1  part  of  ether, 
and  then  titrating  with  decinormal  alcoholic  soda  lye 
and  phenolphtalein.  In  the  case  of  light-colored  oils 
this  may  be  done  directly;  dark  oils,  however,  must 


OILS  AND  FATS.  97 

first  be  shaken  with  double  the  volume  of  absolute 
alcohol,  allowed  to  stand  for  several  hours,  and  the 
titration  effected  with  20  cc.  of  the  alcohol  as  above. 

In  addition,  the  power  of  attacking  metals  may  be 
tested  by  prolonged  warming  with  polished  metals; 
the  surfaces  of  these  should  not  be  affected.  In  the 
case  of  bearing  metals,  a  heat  of  50°  C.  suffices;  in  the 
case  of  steam-cylinder  oils,  these  must  be  heated  in 
autoclaves  at  the  temperature  to  which  the  oils  will 
be  subjected  in  practice.  An  attack  on  the  metal  here 
takes  place  almost  always  only  in  the  case  of  an  admix- 
ture of  fatty  oils,  the  presence  of  which  may  be  directly 
detected  by  the  formation  of  a  soap  on  heating  for  15 
minutes  with  caustic  soda  in  a  paraffin-bath  at  a  tem- 
perature of  230°  to  250°  C. 

OILS  AND  FATS. 

It  is  but  seldom  that  fatty  oils  or  solid  fats  can 
be  decomposed  into  their  individual  constituents.  By 
means  of  a  number  of  reactions  it  is  possible  to  quan- 
titatively ascertain,  however,  how  many  of  the  indi- 
vidual groups  of  glycerides  are  present,  and  to  thereby 
quite  easily  characterize  the  fats  and  oils.  The  results 
are  expressed  in  the  form  of  numbers,  which  are  some- 
times also  designated  by  the  names  of  the  chemists 
who  first  advanced  their  use.  These  reactions  are  as 
follows :  * 

1.  The  Hehner  number  indicates   the  percentage  of 

*  For  further  particulars  see  Chem.-Techn,  Untersuchungs- 
jnethoden,  III,  p.  88  et  sey. 


98  TECHNO-CHEMICAL  ANALYSIS. 

water-insoluble  fatty  acids  present  (those  soluble  in 
water  are  the  lower  volatile  fatty  acids  only).  Saponify 
3  to  5  grm.  of  the  fat  with  alcoholic  alkali,  precipitate 
the  fat  acids  with  a  strong  acid,  collect  them  on  a 
filter,  wash  with  water,  and  weigh. 

2.  The  acid  number  indicates  the  number  of  milli- 
grammes of  KOH  required  to  saturate  the  free  fatty 
acids  in  1  grm.  of  the  substance,  and  it  is  ascertained 
by  titrating  with  seminormal  lye  and  phenolphtalein. 
The  number  of  cubic  centimeters  used  up  multiplied 
by  28  (one -half  the  molecular  weight  of  KOH)  gives 
the  acid  number. 

3.  The  saponification    number    (Kottsorfer)   denotes 
the  number  of  milligrammes  of  KOH  required  to  fully 
saponify    1   grm.    of   the   fat;    alcoholic   lye   is   used 
for  this  purpose,  the  excess  being  titrated  back  with 
seminormal    hydrochloric    acid    and    phenolphtalein. 
The  operation  may  be  conducted  with  the  aid  of  heat/ 
by  boiling  for  half  an  hour  under  a  reflux  condenser, 
or  hi  the  cold  by  dissolving  in  petroleum  ether  (accord- 
ing to  Henriques). 

4.  The  Hubl  iodine  number  affords  an  insight  as  to  the 
content  of  unsaturated  acids;   it  indicates  the  number 
of  grammes  of  iodine  that  are  capable  of  combining  with 
100  grammes  of  fat.     For  this  there  is  employed  an  alco- 
holic, approximately  1/5-normal,  solution  of  iodine  and 
mercuric  chloride ;   an  excess  of  the  solution  is  allowed 
to  act  upon  the  fat  dissolved  in  chloroform,  potassium 
iodide  then  added,  and  the  excess  of  iodine  then  titrated 
back  with  sodium  thiosulphate, 


OILS  AND  FATS.  99 

5.  The   acetyl   number  gives   the   quantity  of  oxy- 
acids  present  which  are  acetylated  by  treatment  with 
acetic  anhydride.     This  method  is  rather  difficult  to 
carry  out,   and  even   then   does  not   give  certain  re- 
sults. 

6.  The  Reichert-Meissl  number  refers  to  the  content 
of  volatile  acids,  and  denotes  the  number  of  cubic  centi- 
meters of  decinormal  alkali-lye  required  to  neutralize 
the  acids  volatilized  by  steam  and  soluble  in  water, 
and  which  are  obtained  by  saponifying  5  grm.  of  the 
fat. 

In  addition  there  are  determined  the  specific  gravity, 
melting-point,  solidifying-point,  and  refractive  index, 
the  latter  being  ascertained  by  means  of  the  Zeiss  refrac-. 
tometer,  the  use  of  which  is  made  obligatory  for  butter; 
the  odor  and  taste  are  also  noted. 

The  presence  of  certain  oils  may  be  qualitatively 
determined  by  reactions,  e.g.,  sesame  oil  by  the  rose- 
red  color  afforded  by  an  alcoholic  solution  of  furfurol 
(Baudouin's  reaction) ;  cottonseed-oil  by  the  reduction 
of  silver  nitrate  (Bechi's  reaction);  or  the  orange-red 
color  afforded  by  a  mixture  of  amylic  alcohol  and  car- 
bon disulphide  (Halphen's  reaction). 

Of  the  foreign  constituents,  the  water  is  determined 
by  drying  at  100°  C. ;  the  inorganic  constituents  by  incin- 
eration; the  organic  non-fatty  substances  (dirt  of  all 
kinds)  by  dissolving  in  ether  and  filtering;  free  mineral 
acids  by  boiling  with  water  and  titrating  the  solution 
with  decinormal  soda  lye  and  methyl  orange;  soaps 
(in  solid  fats)  by  incinerating,  and  titrating  the  alkaline 


100  TECHNO-CHEMICAL  ANALYSIS. 

ash;   non-saponifiable  oils  by  boiling  with  an  alcoholic 
alkali  solution  and  then  diluting  with  water. 

An  admixture  of  resin  is  recognized  by  the  compara- 
tively high  acid  number,  by  the  solubility  in  70-per- 
cent, alcohol,  and  also  by  shaking  with  acetic  anhydride, 
when,  on  the  addition  of  a  drop  of  sulphuric  acid 
(sp.  gr.  1.53),  a  reddish-violet  color  develops  (Storch- 
Morawski  reaction). 

SOAPS. 

In  taking  the  sample,  due  regard  must  be  paid  to  the 
fact  that  the  surface  of  the  soap  rapidly  dries,  and  that 
hence  the  external  layer  must  be  removed;  and  in  the 
case  of  soft  soaps,  all  those  parts  that  have  been  ex- 
posed to  the  air.  The  following  determinations  are 
then  made : 

a.  Water. — Weigh  off  5  to  10  grm.  of  the  sample  in 
a  small  dish,  heat  for  two  hours  in  a  drying-closet  at 
60°-70°  C.,  then  for  half  an  hour  at  105°-110°  C.,  and 
weigh. 

b.  Inorganic  Fillers. — Boil  30  grm.  of  the  sample  with 
absolute  alcohol,  which  will  leave  behind  all  the  salts 
of  the  mineral  acids  (with  C02,  Si02,  B203,  S03,  Cl); 
then  filter,  wash  with  alcohol,  and  weigh  after  drying. 
The  mixture  of  salts  may  then  be  investigated  for  its 
individual  constituents  by  the  usual  methods. 

c.  Total  Fat  and  Total  Alkali. — These  may  be  deter- 
mined in  one  operation,  by  decomposing  a  weighed 
sample  with  normal  acid,  and  adding  a  solvent  for  the 


SOAPS.  101 

fats;  the  uncombined  acid  in  the  aqueous  solution  is 
then  determined  by  titrating  back,  while  the  fatty 
acids  are  estimated  by  evaporating  an  aliquot  portion 
of  the  fat-acids  solution.  For  this  purpose  Huggen- 
berg  has  constructed  a  peculiarly  shaped  burette,  which 
admirably  accomplishes  its  purpose.  But  even  with- 
out this  apparatus  excellent  results  may  be  obtained 
as  follows:  Heat  5  to  10  grm.  with  diluted  hydrochloric 
or  sulphuric  acid  until  the  separated  fatty  acids  float 
as  a  clear,  oily  layer,  then  add  5  to  10  grm.  of  remelted 
wax  or  hard  paraffin,  with  which  the  fatty  acids  form 
a  difficultly  fusible  mass,  and  allow  to  cool.  The  acid 
liquid  is  poured  off,  the  fat-cake  remelted  once  or 
twice  with  water,  then  removed,  the  adhering  water 
allowed  to  drain  off,  and  the  cake  then  placed  in  an 
exsiccator  for  several  hours  before  weighing.  It  is 
convenient  to  weigh  a  piece  of  filter-paper  together 
with  the  wax,  so  that  it  may  be  used  for  wiping  the 
vessels,  removing  fat  adhering  to  the  glass  rods,  etc. 

The  fatty  acids  obtained  by  one  method  or  another 
were  of  course  not  naturally  present  in  the  soap  as 
such,  but  (in  a  dualistic  sense)  in  the  form  of  anhy- 
drides combined  with  N20  or  K20;  hence  the  water 
of  hydration  corresponding  to  their  mean  molecular 
weight  must  be  deducted,  and  this  is  generally  assumed 
to  be  equal  to  3.25  per  cent,  of  their  weight. 

The  total  alkali  may  be  more  rapidly  determined  by 
itself  by  decomposing  about  2  grm.  of  the  soap  with  a 
measured  volume  of  normal  acid  with  the  aid  of  heat, 
allowing  to  cool,  adding  methyl  orange,  and  titrating 


102  TECHNO-CHEMICAL  ANALYSIS. 

back  with  normal  soda  lye  without  separating  the 
fatty  acids. 

The  free  alkali  present  (i.e.,  the  carbonate  and  hydrate) 
is  most  simply  determined  by  boiling  20  to  50  grm. 
of  the  soap  with  about  100  cc.  of  a  neutral,  saturated 
solution  of  sodium  chloride,  filtering,  and  titrating  the 
solution  with  methyl  orange  and  1/5-normal  acid. 

Glycerin  is  found  in  large  quantity  only  in  toilet 
soaps.  The  method  of  determining  it  is  given  here, 
because  it  must  be  examined  by  itself  as  an  individual 
commercial  article,  and  the  glycerin  yield  of  raw  fats 
in  the  manufacture  of  stearin  must  also  be  determined. 
The  determination  is  effected  either  by  oxidation  with 
potassium-permanganate  solution  in  alkaline  solution, 
precipitating  the  oxalic  acid  formed  as  a  lime  salt,  and 
titrating  the  latter,  or  by  oxidation  with  normal  potas- 
sium-dichromate  solution,  with  the  addition  of  an 
excess  of  ferrous-sulphate  solution  of  known  effective 
value,  and  then  titrating  with  dichromate  solution. 

Pure  glycerin  should  be  colorless,  almost  free  from 
ash,  of  sweet  taste  and  odor,  and  have  a  specific  grav- 
ity of  1.26. 

SUGAR. 

Sugar-beets. — As  good  an  average  sample  as  possi- 
ble is  taken,  and  reduced  without  loss  of  juice  to  a 
homogeneous  pulp  (for  which  purpose  quite  a  number 
of  various  apparatus  have  been  devised);  in  this 
the  sugar  content  is  determined,  usually  by  polariza- 
tion. 


SUGAR.  103 

For  this  purpose  the  Soleil-Ventzke-Scheibler  polar- 
izer, improved  by  Schmidt  and  Haensch,  is  used.  The 
scale  of  the  apparatus  is  so  arranged  that  when  26.048 
grm.  of  sugar  are  dissolved  in  enough  water  to  make 
100  cc.,  and  the  solution  examined  in  a  200-mm.  tube 
at  a  temperature  of  17.5°  C.,  the  plane  of  polarization 
will  be  turned  100°,  and  hence  every  degree  will  indi- 
cate 0.26048  grm.  of  sugar  in  100  cc.  of  solution.  Hence 
if  26.048  grm.  of  any  sugar  or  saccharine  substance  be 
weighed  off  and  dissolved  to  make  100  cc.  of  solution, 
and  the  latter  observed  through  a  200-mm.  tube  at 
17.5°  C.;  the  deviation  will  give,  without  further  cal- 
culation, the  percentage  content  of  sugar  by  a  simple 
reading  of  the  scale.  It  is  absolutely  essential  to 
accurately  control  the  temperature. 

The  beet  pulp  is  next  subjected  to  alcohol  extraction 
in  a  Soxhlet  apparatus.  To  26.048  grm.  of  the  beet 
pulp,  3  cc.  of  lead-subacetate  solution  are  added,  and 
the  mixture  extracted  with  75  cc.  of  90-per-cent.  alco- 
hol until  exhausted,  which  will  usually  require  at  most 
two  hours.  If  it  is  desired  to  make  quite  certain  that 
the  exhaustion  is  complete,  the  residue  is  again  ex- 
tracted for  half  an  hour  in  another  apparatus.  The 
alcoholic  extract  is  then  made  up  to  100  cc.  and  polar- 
ized as  detailed  above.  The  various  other  methods  of 
digestion  are  less  trustworthy. 

Furthermore,  the  s'olid  constituents  of  the  beets 
(the  "marc")  insoluble  in  water  are  also  determined 
by  leaching  with  water  and  drying  the  residue  at  110°  C., 
best  in  a  vacuum  drying-closet. 


104  TECHNO-CHEMICAL  ANALYSIS. 

The  polarization  does  not  give  directly  the  content 
of  cane-sugar,  because  there  are  also  other  optically 
active  substances  present,  chiefly  invert-sugar,  of  which 
1  part  gives  the  optical  rotation  afforded  by  0.34  parts 
of  cane-sugar.  The  invert-sugar  is  determined  by  its 
property  of  precipitating  copper  in  the  form  of  red 
Cu20  from  a  boiling  alkaline  copper  solution.  To  pre- 
pare the  copper  solution  (Fehling's  solution),  dissolve 
(according  to  Soxhlet's  formula)  34.639  grm.  of  chem- 
ically pure  copper  sulphate  in  enough  distilled  water 
to  make  500  cc.;  on  the  other  hand,  dissolve  173  grm. 
of  the  purest  Rochelle  salt  in  somewhat  less  than  400  cc. 
of  water,  add  100  cc.  of  a  solution  of  516  grm.  of  the 
purest  NaOH  in  1  liter  of  water,  and  make  up  to  500  cc. 
Both  solutions,  which  must  be  perfectly  clear,  must 
be  kept  separately,  and  equal  volumes  of  the  two 
mixed  just  before  use.  The  mixture  remains  in  a 
serviceable  condition  but  for  a  few  days.  It  is  em- 
ployed either  gravimetrically  or  volumetrically. 

In  the  former,  the  method  of  procedure,  where  at 
most  1  per  cent,  of  invert-sugar  is  present  besides  the 
cane-sugar,  is  as  follows:  In  the  case  of  rather  pure 
products  20  grm.  are  dissolved  to  make  100  cc.  of 
solution,  the  liquid  filtered,  and  50  cc.  taken  for  the 
determination.  In  the  case  of  more  impure  products, 
25  grm.  are  dissolved  with  a  little  lead-subacetate 
solution  to  make  100  cc.,  the  lead  removed  from  60  cc. 
of  filtrate  by  means  of  sodium  bicarbonate,  the  solution 
made  up  to  75  cc.,  and  50  cc.  (=10  grm.  of  substance) 
of  the  filtrate  taken  for  analysis.  The  sample  is  mixed 


SUGAR.  105 

in  a  300-cc.  Erlenmeyer  flask  with  50  cc.  of  freshly 
prepared  Fehling's  solution,  the  mixture  heated  as 
rapidly  as  possible  to  boiling,  and  maintained  at  this 
point  for  two  minutes,  and  then  immediately  diluted 
with  100  cc.  of  cold,  air-free  distilled  water,  and  filtered 
by  means  of  an  air-pump  through  a  previously  weighed 
Soxhlet  asbestos  filter.  The  latter  is  a  glass  cylinder  2 
cm.  wide  and  12  to  14  cm.  long,  constricted  at  one  end 
to  form  a  cone.  The  conical  end  bears  a  platinum  cone, 
above  which  is  placed  a  2-cm.  layer  of  purest  asbestos. 
After  filtering  as  above  detailed,  wash  the  residue  with 
300  to  400  cc.  of  boiling  water,  then  with  20  cc.  of  abso- 
lute alcohol,  dry  at  130°  to  200°  C.,  heat  to  faint  red- 
ness, and  reduce  to  metallic  copper  by  prolonged 
heating,  finally  igniting  gently  in  a  current  of  hydro- 
gen. (A  table  for  the  calculation  of  the  percentage 
content  of  invert-sugar  will  be  found  in  Chem.-Techn. 
Untersuchungsmethoden,  III, 'p.  285.) 

When  higher  percentages  of  invert-sugar  are  present 
smaller  quantities  of  the  substance  are  weighed  off,  and 
the  procedure  then  carried  out  as  above.  The  calcula- 
tion made  by  aid  of  the  polarizing  apparatus  is  rather 
complicated  in  this  case,  hence  it  is  better  to  determine 
the  total  sugar  by  inversion,  and  then  to  deduct  the 
invert  sugar  found  directly  as  above,  in  order  to  obtain 
the  pure  saccharose  (cane-sugar). 

To  effect  inversion,  i.e.,  conversion  of  the  saccharose 
into  sugars  having  the  composition  of  dextrose  (invert- 
sugar),  heat  13.024  grm.  of  sugar  with  75  cc.  water 
and  5  cc.  concentrated  hydrochloric  acid  in  a  water- 


106  TECHNO-CHEMICAL  ANALYSIS. 

bath  to  67°  C.,  maintain  at  this  temperature  for  five 
minutes,  then  cool  immediately,  and  make  up  to  100  cc., 
and  then  dilute  50  cc.  with  water  to  make  1  liter;  of  this 
solution  take  25  cc.  ( =0.1628  grm.  substance),  neutralize 
the  free  acid  by  gradually  adding  25  cc.  of  a  solution 
of  1.7  grm.  Na2C03  in  1  liter  of  water,  then  add  50  cc. 
Fehling's  solution,  heat  to  boiling,  boil  for  2  minutes, 
and  convert  the  Cu20  into  Cu  as  detailed  on  pages  104 
and  105.  Every  100  mgm.  of  Cu  will  correspond  to 
30.93  per  cent,  of  total  sugar,  calculated  as  cane-sugar. 

Fehling's  solution  may  also  be  utilized  for  the  volu- 
metric determination  of  invert-sugar. 

Saccharine  juices  are  first  tested  as  to  their  specific 
gravities,  then  measured  in  a  Balling-Brix  saccharom- 
eter,  the  degrees  of  which  in  the  case  of  solutions  of 
pure  sugar  give  directly  the  percentage  of  sugar,  but 
in  the  case  of  the  impure  factory  products  they  give 
only  the  total  (apparently)  dry  substance.  A  direct 
determination  of  the  sugar  content  is  effected  by  polar- 
izing as  on  page  103,  after  adding  lead-subacetate  solu- 
tion to  clarify  the  solution  and  remove  the  non-sugars. 
There  are  also  determined  the  water  content,  by  evapo- 
rating with  quartz  sand  at  105°  to  110°C.;  the  ash 
content;  the  content  of  invert-sugar  (usually  by  titra- 
tion  with  Fehling's  solution);  the  alkalinity,  by 
titrating  with  very  dilute  normal  acid  and  phenol- 
phtalein;  and  the  lime  content  by  precipitating  with 
ammonium  oxalate. 

The  other  factory  products,  as  well  as  molasses,  are 
examined  in  a  similar  manner. 


ALCOHOL.  107 

For  the  examination  of  sugar  itself  (cane-sugar  and 
refined  sugar),  dissolve  26.048  grm.  in  water  to  make 
100  cc.,  clarify  by  adding  lead-subacetate  solution  or 
(in  the  case  of  pure  sugar)  aluminium-hydrate  cream, 
and  polarize  as  on  page  -103.  In  addition  all  the  other 
factors  may  be  determined,  as  in  the  case  of  beet- 
juices. 

ALCOHOL  MANUFACTURE  (BRANDY,  ETC.). 

Raw  Materials. — In  amylaceous  substances  the  starch 
is  determined  by  converting  it  into  dextrose  by  means 
of  hydrochloric  acid,  the  "  inversion"  being  accom- 
plished by  first  gelatinizing  3  grm.  of  starch  with  200  cc. 
water  and  then  heating  on  a  water-bath  for  two  hours 
with  15  cc.  hydrochloric  acid  of  sp.  gr.  1.125,  loss  of 
vapor  during  heating  being  avoided  by  fixing  a  rather 
long  tube  on  the  flask.  The  mixture  is  then  neutralized 
almost  completely  with  soda  lye,  made  up  to  500  cc., 
and  the  dextrose  determined  as  on  page  104.  Nine  parts 
of  starch  correspond  to  ten  parts  of  dextrose,  and  the 
results  are  calculated  accordingly. 

With  substances  containing  cellulose,  the  inversion 
by  acids  gives  too  high  results  in  cases  where  the  high- 
pressure  method  is  not  employed,  which  method  also 
partially  converts  these  substances  into  fermentible 
bodies.  In  such  cases  the  inversion  is  effected  by 
means  of  malt  extract,  the  reducing  power  of  which 
has  been  previously  determined  by  a  separate  test, 
and  due  allowance  made  for  it. 

Qn  the%  other  hand?  in  the  analysis  by  the  high- 


108  TECHNO-CHEMICAL  ANALYSIS. 

pressure  method,  the  inversion  is  effected  under  pres- 
sure, for  which  purpose  the  Lintner  pressure-flask  is 
employed,  the  stopper  of  which  is  held  fast  by  a  wire 
frame  and  screws. 

The  determination  of  starch  in  potatoes  is  accom- 
plished with  sufficient  accuracy  for  ordinary  practical 
work  (with  an  error  of  +1  per  cent.)  by  determining 
the  specific  gravity  with  a  balance  specially  adapted 
for  the  purpose,  the  determination  being  based  upon 
the  fact  that  the  specific  gravity  of  starch  is  very 
high;  and  the  dry  substance  of  potatoes  consists  chiefly 
of  starch.  A  table  for  this  is  given  in  Chem.-Techn. 
Untersuchungsmethoden,  III,  p.  371. 

Saccharine  raw  materials,  such  as  molasses,  etc.,  are 
examined  by  polarization  (page  103),  or  by  a  direct 
fermentation  test;  e.g.,  by  diluting  50  grm.  of  the 
molasses  with  200  grm.  water,  adding  10  cc.  concentrated 
sulphuric  acid  and  a  little  yeast,  allowing  to  ferment, 
and  then  distilling  off  100  cc.  In  the  distillate  the 
alcohol  is  determined,  and  if  necessary  the  volatile 
acids  also. 

Malt  is  chiefly  examined  as  to  its  saccharifying 
power,  in  addition  to  its  external  characteristics.  6  grm. 
of  crushed  malt  are  digested  with  100  cc.  water  for 
one  hour  on  a  water-bath  at  60°  C.,  and  the  mixture 
then  cooled  and  filtered.  This  malt  extract  is  mixed 
with  soluble  starch.  2  grm.  of  Effront's  or  Lintner's 
soluble  starch  are  dissolved  in  100  cc.  boiling  water, 
50  cc.  of  the  solution  diluted  with  107.5  cc.  water,  and 
2.5  cc,  of  the  malt  extract  added,  Saccharification  is. 


ALCOHOL. 

then  effected  by  heating  for  one  hour  on  a  wat1*r£§g$ A  ^/ 
at  60°  C.,  the  mixture  then  heated  rapidly  to  boiling, 
and  cooled.     The  solution  is  then  tested  for  its  sugar 
content  by  means  of  Fehling's  solution,  and  usually 
volumetrically. 

The  liquefying  power  of  malt  is  furthermore  ascer- 
tained by  warming  with  triturated  rice  starch  at  80°  C. 
The  smaller  the  quantity  of  malt  extract  required  for 
the  purpose,  the  higher  is  its  liquefying  power.  The 
acid  content  too,  which  by  careless  treatment  may  be 
considerably  augmented,  is  determined  by  means  of 
phenolphtalein  in  an  extract  obtained  by  digestion  with 
chloroform  water  (distilled  water  shaken  with  chloro- 
form and  then  poured  off  from  the  latter). 

Sweet  mash  is  examined  as  to  the  extent  of  the 
saccharization  it  has  undergone,  directly  by  means  of 
the  saccharometer  (page  106),  and  indirectly  by  ex- 
tracting with  cold  water  and  determining  the  starch 
in  the  insoluble  residue,  as  on  page  107. 

Fermented  mash  is  examined,  after  filtration,  as  to 
the  extent  it  has  fermented,  by  means  of  the  saccharom- 
eter, which,  however,  gives  only  the  apparent  fermenta- 
tion, as  the  increase  in  the  specific  gravity  of  the  liquid 
due  to  the  sugar  is  to  some  extent  counterbalanced  by 
the  decrease  caused  by  the  alcohol  formed.  The  actual 
content  of  soluble  matter  is  ascertained  by  taking  note 
of  the  alcohol  content.  If  S  be  the  specific  gravity  of 
the  mash  considered  as  free  from  alcohol,  SA  that  of  the 
alcoholic  mash,  and  s  that  of  a  mixture  of  alcohol  and 
water  of  the  same  alcoholic  strength  as  that  of  the  mash, 


110  TECHNO-CHEMICAL  ANALYSIS. 

then  S=S1+(1  — s).  From  S  the  sugar  still  present  is 
then  found  by  means  of  the  tables. 

Maltose  is  determined  by  polarization  in  the  solution 
clarified  by  treatment  with  lead  subacetate  and  freed 
from  lead  with  sulphuric  acid  (page  103)  The  total  car- 
bohydrates are  determined,  after  inversion  with  hydro- 
chloric acid,  by  means  of  Fehling's  solution  (page  104), 
and  then  the  dextrin  content  by  deducting  the  maltose 
from  the  total. 

Alcohol  is  determined  by  distilling  the  mash-filtrate 
and  taking  the  specific  gravity  as  detailed  below. 

Alcoholometry.  —  In  alcohol  and  similar  relatively 
pure  mixtures  of  alcohol  and  water,  the  alcohol  is  ascer- 
tained by  the  specific  gravity,  which  is  taken  with  an 
araeometer  (alcoholometer),  picnometer,  or  a  hydro- 
static balance.  Absolutely  pure  alcohol,  at  a  tem- 
perature of  15°  C.,  has  a  specific  gravity  of  0.79425. 

The  alcoholometer  officially  used  in  Germany  gives 
directly  the  percentage  by  weight,  and  must  hence  be 
employed  either  at  the  temperature  of  15°  C.,  or  the 
proper  correction  must  be  made  for  other  tempera- 
tures by  means  of  tables  issued  by  the  Normal-Standard 
Commission. 

Frequently,  however,  the  statements  are  also  made  in 
volume-percents,  for  which  either  a  special  alcoholom- 
eter, or  reduction  tables,  must  be  employed.  (Com- 
pare "  Anleitung  zur  steueramtlichen  Ermittelung  des 
Alcohols  im  Branntwein, "  Berlin,  Julius  Springer.) 

Alcohol  is  now  usually  bought  and  sold  by  liter- 
per  cent.,  of  which  each  represents  10  cc.  of  absolute 


ALCOHOL. 


Ill 


alcohol.     Ten  thousand  liter-percent,  is  equivalent  to 
1  hectoliter  absolute  alcohol. 


Specific 
Gravity. 

Grammes 
Alcohol  in 
100  cc. 

Volume 
Per  Cent. 

Specific 
Gravity. 

Grammes 
Alcohol  in 
100  cc. 

Volume 
Per  Cent. 

1.000 

0.00 

0.00 

0.980 

12.81 

16.14 

0.999 

0.53 

0.67 

0.979 

13.60 

17.14 

0.998 

1.06 

1.34 

0.978 

14.39 

18.14 

0.997 

1.60 

2.02 

0.977 

15.19 

19.14 

0.996 

2.16 

2.72 

0.976 

15.99 

20.15 

0.995 

2.72 

3.42 

0.975 

16.79 

21.16 

0.994 

3.29 

4.14 

0.974 

17.58 

22.16 

0.993 

3.87 

4.88 

0.973 

18.37 

23.14 

0.992 

4.47 

5.63 

0.972 

19.14 

24.12 

0.991 

5.08 

6.40 

0.971 

19.91 

25.08 

0.990 

5.70 

7.18 

0.970 

20.66 

26.03 

0.989 

6.34 

7.99 

0.969 

21.40 

26.96 

0.988 

6.99 

8.81 

0.968 

22.12 

27.87 

0.987 

7.66 

9.66 

0.967 

22.82 

28.76 

0.986 

8.35 

10.52 

0.966 

23.52 

29.64 

0.985 

9.06 

11.41 

0.965 

24.19 

30.49 

0.984 

9.78 

12.32 

0.964 

24.85 

31.32 

0.983 

10.52 

13.25 

0.963 

25.50 

32.14 

0.982 

11.27 

14.20 

0.962 

26.13 

32.93 

0.981 

12.03 

15.16 

„ 

The  above  table  gives  the  percentage  of  alcohol 
by  weight  and  volume  at  15°  C.  at  various  specific 
gravities.* 

Fusel-oil  is  determined  by  Rose's  method  and  other 
modifications  by  shaking-out  with  chloroform,  which 
dissolves  the  higher-boiling  homologues  of  ethyl  alcohol 
much  more  readily  than  it  does  alcohol,  and  thereby 
increases  in  volume.  The  apparatus  in  which  the 
shaking  is  done  is  a  glass  tube  expanded  at  both  ends, 

*  A  complete  table  by  K.  Windisch  has  been  published  by  Julius 
Springer,  under  the  title  "  Tafel  fur  Ermittelung  des  Alcoholgehaltes 
von  Alcohol- Wassermisehungen  nach  dem  specifischen  Gewicht." 


112  TECHNO-CHEMICAL  ANALYSIS. 

the  lower  end  terminating  in  a  closed  half-bulb,  and 
the  upper  closed  by  a  cork  stopper.  The  lower  por- 
tion of  the  tube  holds  200  cc.  up  to  the  narrowed  part. 
The  middle,  cylindrical  part  holds  20  to  26  cc.  and  is 
divided  into  1/20  cc.  The  upper  part  is  pear-shaped, 
and  holds  from  150  to  180  cc.  The  brandy  to  be  tested 
is  distilled  with  the  addition  of  a  little  soda  lye.  The 
distillate  is  carefully  examined  in  a  picnometer  for  its 
specific  gravity,  and  diluted  to  an  alcohol  content  of 
24.7  per  cent,  by  weight,  equivalent  to  30  per  cent,  by 
volume.  By  means  of  a  funnel  reaching  to  the  bottom 
of  the  shaking-out  apparatus,  which  has  been  brought  to 
15°  C.,  20  cc.  of  chloroform  are  introduced,  and  by  means 
of  a  fine  pipette,  brought  exactly  to  the  mark.  There 
are  then  added  100  cc.  of  the  alcohol  which  has  been 
reduced  in  strength  to  30  volume-percent,  and  brought 
to  15°  C.,  together  with  5  cc.  of  sulphuric  acid  of  sp.  gr. 
1.286;  the  apparatus  is  now  stoppered,  vigorously  shaken 
150  times,  again  cooled  in  a  water-bath  to  15°  C.,  and 
the  level  of  the  chloroform  in  the  narrow  portion  of  the 
tube  noted  ( =  a) .  Chloroform  takes  up  a  little  alcohol, 
even  when  the  latter  is  perfectly  pure,  hence  the  quantity 
taken  up  must  be  determined  for  each  lot  of  chloroform. 
The  level  of  the  chloroform  after  such  a  control  test  we 
will  designate  as  b.  According  as  a—  b  is  greater  or 
less  than  0.9  cc.,  the  brandy  contains  more  or  less  than 
2  per  cent,  fusel-oil  in  every  2  parts  by  weight  of  anhy- 
drous alcohol.  The  figure  representing  the  percentage 
by  weight  of  fusel-oil  up  to  5  per  cent,  is  obtained  by 
multiplying  a—  b  by  2.22.  In  the  case  of  brandies  very 


VINEGAR.  113 

poor  in  fusel-oil,  special  apparatus  with  finer  gradua- 
tions is  employed. 

Furfurol  is  detected  in  10  cc.  of  the  distillate  by  add- 
ing 10  drops  of  colorless  aniline  and  2  cc.  acetic  acid; 
in  twenty  to  thirty  minutes. a  rose-red  color  develops. 

Of  the  denaturing  substances,  pyridine  is  detected  by 
cadmium  chloride,  which  gives  with  it  a  white,  crystal- 
line precipitate.  If  an  acid  has  been  added  to  the 
brandy  for  the  purpose  of  removing  the  pyridine  odor? 
the  cadmium-chloride  reaction  does  not  occur,  but  it 
develops  immediately  on  shaking  with  magnesia.  Ace- 
tone is  indicated  by  the  formation  of  iodoform  on  adding 
ammonia  and  a  solution  of  iodine  in  ammonium-iodide 
solution. 

The  differentiation  of  the  various  grades  of  brandy 
from  each  other  is  far  easier  of  accomplishment  by 
means  of  the  odor  and  taste  than  by  chemical  investi- 
gation. 

VINEGAR. 

The  total  acid  is  determined  by  titration  with  nor- 
mal alkali,  using  phenolphtalein  as  indicator;  in  highly 
colored  vinegar  the  "spot"  method  is  employed,  using 
good  litmus  paper. 

Free  mineral  acids  are  detected  by  diluting  the 
vinegar  to  a  2-per-cent.  strength  and  adding  a  few 
drops  of  a  1/100-per-cent.  solution  of  methyl  violet, 
which,  in  the  presence  of  a  considerable  quantity  of 
mineral  acid,  imparts  a  green  color,  and  with  very 
small  quantities  of  mineral  acids,  a  blue  color,  to  the 


114  TECHNO-CHEMICAL  ANALYSIS. 

liquid.  Sulphuric  acid  particularly  is  detected  by 
evaporating  a  small  quantity  of  the  vinegar  with  a 
little  starch  to  one-fifth  of  its  volume  and  adding 
iodine  solution;  if  free  sulphuric  acid  is  absent  the 
starch  will  be  colored  blue,  but  if  the  starch  has  been 
converted  into  sugar  by  inversion  with  sulphuric  acid, 
no  blue  color  will  develop.  Or,  a  little  of  the  vinegar 
is  evaporated  to  dryness  on  the  water-bath  with  a 
little  sugar,  whereby  a  black  ring  will  form,  due  to  the 
carbonization  of  the  sugar  by  the  sulphuric  acid. 
Hydrochloric  acid  or  nitric  acid  is  detected  by  distilling, 
and  testing  the  distillate  in  the  usual  manner.  Tar- 
taric  acid  is  detected  by  evaporating,  taking  up  the 
residue  with  alcohol,  and  adding  potassium  chloride, 
when  a  precipitate  of  potass' um  bitartrate  forms. 
Oxalic  acid  is  recognized  by  the  precipitate  afforded  by 
calcium-sulphate  solution. 

If  foreign  acids  are  present,  or  if  the  vinegar  is  highly 
colored,  the  acetic  acid  is  determined  directly  by  neu- 
tralization with  alkali,  supersaturation  with  phosphoric 
acid,  then  distilling  in  a  water-bath  by  the  aid  of  a 
current  of  steam,  and  finally  titrating  the  distillate. 

Poisonous  metals  are  detected  and  determined  by 
the  methods  employed  in  mineral  analysis. 

Wood-vinegar  contains  chiefly  empyreumatic  con- 
stituents, which  are  detected  by  the  decolorization  of  a 
decinormal  potassium-permanganate  solution.  Nor  does 
it  contain  the  micro-organisms  which  occur  in  fermen- 
tation vinegar,  and  which  may  be  microscopically 
detected  in  the. latter. 


WlXE.  115 


WINE.* 

Of  the  methods  for  examining  wines,  officially  pub- 
lished by  the  Chancellor  of  the  Empire,  and  based  on 
the  Food  Laws  of  1896,  only  the  more  important  will 
be  given  here. 

The  specific  gravity  is  determined  with  a  picnometer, 
and  the  alcohol  by  distilling,  and  testing  the  distillate 
according  to  the  table  given  on  page  111;  the  content 
of  extract  "E"  is  ascertained  according  to  the  table  on 
page  118,  after  determining  the  density  "x"  by  means 
of  the  formula  z  =  l  +  S— S^  where  S  is  the  specific 
gravity  of  the  distillate,  and  Sx  that  of  the  residue 
which  has  remained  after  the  distillation  and  which 
has  been  made  up  to  the  original  volume.  The  mineral 
constituents  are  determined  by  incineration;  the  sulphuric 
acid  (in  red  wine)  is  determined  by  precipitation  with 
barium  chloride ;  the  total  acid  by  hot  titration  with  a  not 
less  than  one-fourth  normal  lye,  employing  the  "  spot  " 
method  with  violet  litmus  paper  (the  results  being  cal- 
culated as  potassium  bitartrate);  the  volatile  acids  are 
estimated  by  distilling  in  a  current  of  steam;  glycerin 
is  determined  by  evaporating  with  quartz-sand  and 
milk-of-lime  to  dryness,  extracting  the  residue  with 
96-per  cent,  alcohol,  shaking  out  with  ether,  and  evap- 
orating the  ethereal  solution;  sugar  is  determined  with 


*  Compare  K.  Windisch, "  Die  chemische  Untersuchung  und  Beur- 
teilung  des  Weines,"  Berlin,  1896,  and  Th.  W.  Fresenius,  "  Anleitung 
zur  chemischen  Untersuchung  des  Weines,"  Wiesbaden,  1898. 


116  TECHNO-CHEMICAL  ANALYSIS. 

Fehling's  solution  (page  104),  or  by  clarifying  with  lead 
subacetate  and  then  polarizing  (page  103);  impure 
starch-sugar  is  estimated  by  comparing  the  results 
obtained  by  both  these  methods,  as  the  impurities 
polarize  differently  than  does  pure  sugar;  foreign  dyes 
are  detected  by  various  methods  which  can  not  be  given 
here;  potassium  bitartrate  and  tartaric  acid  are  deter- 
mined together  by  converting  the  latter  into  potassium 
bitartrate  and  precipitating  the  total  bitartrate  with 
calcium  chloride;  sulphurous  acid  is  determined  by  dis- 
tilling with  the  addition  of  phosphoric  acid,  collecting 
the  distillate  in  iodine  solution,  and  precipitating  the 
sulphuric  acid  formed  with  barium  chloride;  tannin  is 
determined  by  the  usual  methods  (page  119  et  seq.). 

BEER  BREWING. 

Hops  are  usually  examined  chemically  only  as  to  the 
water  content  and  sulphurization,  the  former  by  drying 
for  four  hours  at  100°  C.  To  find  whether  the  hops 
have  been  sulphurized,  extract  10  grm.  of  the  hops 
with  200  cc.  distilled  water,  and  introduce  50  cc.  of  the 
filtrate  together  with  1.5  grm.  sulphur-free  zinc  and 
25  cc.  pure  hydrochloric  acid  of  sp.  gr.  1.125  into  a  flask, 
which  is  then  covered  with  moist  lead-acetate  paper; 
if  the  latter  is  blackened  within  half  an  hour  by  the 
H2S,  it  indicates  that  S02  had  been  present. 

Barley  too  must  be  occasionally  examined  as  to 
whether  it  has  been  sulphurized. 

In  malts  it  is  chiefly  necessary  to  determine  the 
extract,  which  is  done  by  heating  50  grm.  of  the  malt 


BEER  BREWING.  H7 

with  200  cc.  of  water  for  half  an  hour  at  35°  C.,  then  for 
twenty-five  minutes  at  70°  C.,  and  then  digesting  for 
an  hour  longer  with  constant  stirring;  frequent  tests 
are  then  made  with  iodine  as  to  the  extent  of  saccharifi- 
cation,  and,  when  an  iodine  reaction  is  no  longer  ob- 
tained, the  mixture  is  cooled  by  at  once  adding  200  cc. 
of  cold  water,  the  temperature  rapidly  reduced  to  15°  C., 
and  the  weight  made  up  on  the  balance  to  450  grm. 
The  specific  gravity  of  the  filtrate  is  taken  at  15°  C., 
and  from  this  the  extract  content  is  ascertained  by  ref- 
erence to  Windisch's  table  (page  118). 

The  wort  is  examined  as  on  page  109,  but  in  addition, 
as  to  its  color,  by  colorimetric  comparisons  with  normal 
type  solutions  prepared  from  iodine,  or  better,  from 
artificial  dyes. 

Beer  is  examined  as  to  its  specific  gravity;  its 
alcohol  content  A,  by  distillation,  as  detailed  on  page 
110;  its  extract  content  E,  in  the  residue  from  the  latter, 
as  described  on  page  115;  degree  of  fermentation  V, 
by  comparing  that  of  the  stock  wort,  e,  ascertained 
from  the  alcohol  content  A  according  to  the  for- 

100(E  +  2.0665A) 
mula     inn  i  i  HAA^A  —  »  with  that  of  the  extract  content 

1UU  ~r  1  . 


E,  according  to  the  proportion  e  :  e  —  E  ::  100  :  V; 
whence  V  =  l(X)(l—  V  The  value  of  V  will  lie  be- 

tween 50  and  60  per  cent.,  and  is  legally  fixed  in  vari- 
ous countries.  There  may  furthermore  be  determined, 
among  other  substances,  the  following:  Sugar,  as  in 
wine,  on  pages  115  and  116;  nitrogenous  constituents,  ac- 


TECHNO-CHEMICAL  ANALYSIS. 


cording  to  KjeldahPs  method  (page  80) ;  acids,  by  titra- 
tion  with  phenolphtalein  and  decinormal  lye;  carbonic 
acid,  by  moderately  heating,  at  first  in  a  vacuum,  then  in 
a  current  of  air,  drying  the  gas,  and  collecting  in  potash 
bulbs;  glycerin,  as  detailed  on  page  102;  sulphurous 

EXTRACT  TABLE.* 
x  =  Density  at  15°  C. ;  E  =  Per  cent,  of  extract. 


X 

E 

X 

E 

X 

E 

X 

E 

.000 

0.00 

1.029 

7.50 

1.058 

15.03 

1.087 

22.62 

.001 

0.26 

.030 

7.76 

1.059 

15.29 

1.088 

22.88 

.002 

0.52 

.031 

8.02 

1.060 

15.55 

1.089 

23.14 

.003 

0.77 

.032 

8.27 

1.061 

15.81 

1.090 

23.41 

.004 

1.03 

.033 

8.53 

1.062 

16.07 

1.091 

23.67 

.005 

1.29 

.034 

8.79 

1.063 

16.33 

1.092 

23.93 

.006 

1-55 

.035 

9.05 

1.064 

16.60 

1.093 

24.20 

.007 

1.81 

.036 

9.31 

1.065 

16.86 

1.094 

24.46 

.008 

2.07 

.037 

9.57 

1.066 

17.12 

1.095 

24.72 

.009 

2.32 

1.038 

9.83 

1.067 

17.38 

1.096 

24.99 

.010 

2.58 

1.039 

10.09 

1.068 

17.64 

1.097 

25.25 

.011 

2.84 

1.040 

10.35 

1.069 

17.90 

1.098 

25.51 

.012 

3.10 

1.041 

10.61 

1.070 

18.16 

1.099 

25.78 

.013 

3.36 

1.042 

10.87 

1.071 

18.43 

1.100 

26.04 

.014 

3.62 

.043 

11.13 

1.072 

18.69 

1.101 

26.30 

.015 

3.87 

.044 

11.39 

1.073 

18.95 

1.102 

26.56 

.016 

4.13 

.045 

11.65 

1.074 

19.21 

1.103 

26.83 

.017 

4.39 

.046 

11.91 

1.075 

19.47 

1.104 

27.09 

.018 

4.65 

.047 

12.17 

1.076 

19.73 

1.105 

27.35 

.019 

4.91 

.048 

12.43 

1.077 

20.00 

1.106 

27.62 

.020 

5.17 

.049 

12.69 

1.078 

20.26 

1.107 

27.88 

.021 

5.43 

.050 

12.95 

1.079 

20.52 

1.108 

28.15 

.022 

5.69 

.051 

13.21 

1.080 

20.78 

1.109 

28.41 

.023 

5.94 

.052 

13.47 

1.081 

21.04 

1.110 

28.67 

.024 

6.20 

.053 

13.73 

1.082 

21.31 

.111 

28.94 

.025 

6.46 

.054 

13.99 

1.083 

21.57 

.112 

29.20 

.026 

6.72 

.055 

14.25 

1.084 

21.83 

.113 

29.47 

.027 

6.98 

1.056 

14.51 

1.085 

22.09 

.114 

29.73 

.028 

7.24 

1.057 

14.77 

1.086 

22.36 

.115 

29.99 

*  This  table  is  a  short  abstract  of  that  published  by  K.  Windisch 
under  the  title  Tafel  zur  Ermittelung  des  zuckergehaltes  wassriger 
Zuckerlosungen  aus  der  Dichte  bei  15°  C.,  Berlin,  Jul.  Springer, 
1896. 


TANNING  MATERIALS. 

acid,  by  distilling  with  phosphoric  acid,  collect! 
(distillate  in  iodine  solution,  and  determining  the  sul- 
phuric acid  formed;  and  boric  acid,  by  carbonizing  the 
beer,  to  which  a  little  alkali  has  been  added,  and  testing 
the  acidulated  ash-extract  with  curcuma-paper,  etc. 

TANNING  MATERIALS. 

The  taking  of  the  sample  of  these  substances  pre- 
sents some  difficulty;  it  is  best  accomplished,  as  well 
as  the  analysis,  according  to  the  conclusions  arrived  at 
by  the  international  conference  of  leather  chemists, 
which  will  be  found  in  the  Chem.-Techn.  Untersuch- 
ungsmethoden,  III,  p.  574  et  seq.  From  the  prepared 
sample  the  tannin  is  extracted,  and  the  solution  made 
of  such  strength  that  100  cc.  will  yield  from  0.6  to  0.8 
grm.  residue.  For  this  purpose  weigh  off,  according  to 
the  nature  of  the  material,  from  12  to  50  grm.  of  the 
raw  tanning  material,  and  treat  in  a  suitable  extraction 
apparatus  (for  which  purpose  a  number  have  been 
devised  of  various  construction)  with  water,  first  at 
50°  C.,  and  then  at  100°  C.,  until  500  cc.  of  extract  are 
obtained,  which  is  then  diluted  to  1  liter.  In  the  case 
of  extracts,  dissolve  9  to  20  grm.  in  boiling  water, 
rapidly  cool  to  15°  to  20°  C.,  make  up  to  1  liter,  and 
filter. 

In  this  extract  there  are  determined: 

1.  The  total  soluble  matter  by  evaporating  100  cc. 
and  drying  at  100°  to  105°  C.,  and  best  by  drying  at 
100°  C.  in  a  vacuum  to  constant  weight;  and 


120  TECHNO-CHEMICAL  ANALYSIS. 

2.  The  non-tannins,  by  removing  the  tannin  with 
hide  powder,  and  again  evaporating  the  filtrate.  The 
commercial  hide  powder  must  first  be  well  washed, 
and  then  introduced  into  a  Procter  filter.  The  latter 
consists  of  a  bottomless  flask  of  about  30  cc.  capacity, 
the  open  bottom  being  closed  by  a  piece  of  muslin;  in 
the  neck  is  fastened  a  siphon,  formed  from  a  glass  tube 
bent  twice  at  right  angles  and  having  a  diameter  of 
2  mm.  This  filter  holcls  about  7  grm.  of  hide  powder, 
and  is  placed  in  a  beaker  of  150  to  200  cc.  capacity,  in 
which  100  cc.  of  the  tannin  solution  are  poured,  where- 
upon the  siphon  is  set  in  operation  by  applying  suction. 
The  filtration  requires  from  1J  to  2  hours  for  comple- 
tion. The  first  30  cc.  are  rejected,  and  the  non-tannins 
determined  in  the  next  50  cc.  of  liquid. 

Instead  of  effecting  the  determination  gravimetrically, 
it  is  more  usual  to  employ  the  volumetric  method  de- 
vised by  von  Schroeder  and  improved  by  Lowenthal, 
the  titration  being  effected  with  potassium-perman- 
ganate solution  as  follows: 

a.  Dissolve  2  grm.  of  pure  commercial  tannin  in  1  liter 
of  water,  and  to  10  cc.  of  the  solution  add  20  cc.  of  an 
indigo  solution  prepared  by  dissolving  30  grm.  sodium 
indigosulphonate  in  6  liters  of  10-per-cent.  sulphuric 
acid  and  filtering;  the  20  cc.  should  reduce  about  10.7 
cc.  of  the  permanganate  solution,  and  this  must  be 
ascertained  by  a  test.  Into  the  tannin-indigo  mixture 
now  run  from  a  burette  permanganate  solution  (10  grm. 
purest  KMn04  dissolved  in  6  liters  of  water).  1  cc. 
of  the  permanganate  solution  is  added  at  a  time,  the 


DYEING.  121 

liquid  being  vigorously  stirred  for  5  to  10  seconds  after 
each  addition.  When  the  liquid  acquires  a  light-green 
color  the  permanganate  is  added  by  drops  only,  stir- 
ring after  each  addition,  and  ceasing  when  the  liquid 
appears  golden-yellow.  It  is  inadmissible  to  titrate 
back. 

6.  A  second  titration  is  now  made  after  50  cc.  of 
the  tannin  solution  have  been  digested  with  3  grm.  of 
hide  powder  for  18  to  20  hours.  If  the  quantity  of 
permanganate  solution  used  up  in  6  is  not  more  than 
10  per  cent,  above  what  was  used  in  the  first  titration, 
a,  then  the  tannin  is  suitable  for  preparing  the  standard 
solution.  The  tannin  is  then  dried  at  100°  C.,  the  per- 
manganate solution  used  up  in  a  calculated  for  the  dried 
tannin,  and  the  result  multiplied  by  1.05,  which  will 
give  the  "'true  titer."  In  making  the  determination 
of  tanning  materials  in  the  extracts  prepared  as  above 
(page  119),  the  procedure  is  exactly  the  same  as  in 
fixing  the  titer  in  the  case  of  pure  tannin,  and  the 
result  is  calculated  on  this. 

DYEING.* 

Textile  Fibers. — The  microscope  is  indispensable  for 
the  examination  and  differentiation  of  these.  There 
are,  however,  a  number  of  chemical  reactions  also,  that 
may  be  employed  for  their  differentiation.  The  most 
important  are  the  following: 


*  Compare  R.  Gnehm,  Taschenbuch  fur  Farberei  und  Farben- 
fabrikation,  Berlin,  1902. 


122  TECHNO-CHEMICAL  ANALYSIS. 

Fuchsine  solution  and  the  acid  tar  dyes,  particularly 
picric  acid,  color  animal  fibers  (wool  and  silk),  but  not 
linen  or  cotton.  Concentrated  zinc-chloride  solution 
(sp.  gr.  1.7)  easily  dissolves  silk,  wool  only  partially, 
and  plant  fibers  not  at  all.  Ammoniacal  copper  solu- 
tion dissolves  only  plant  fibers,  whereas  ammoniacal 
nickel  solution  dissolves  silk  only.  Potassa  or  soda,  lye 
dissolves  only  wool  and  silk.  Iodine  and  sulphuric 
acid  color  only  plant  fibers  (with  swelling  of  the  latter) 
linen  and  cotton  blue,  and  hemp  and  jute  greenish  to 
brown.  Sugar  and  sulphuric  acid  color  only  animal 
fibers  a  rose-red  (furfurol  reaction).  Wood  fiber  in 
hemp,  jute,  etc.,  is  detected  by  the  yellow  color  afforded 
with  aniline  sulphate,  by  the  orange  color  developed  by 
naphtylamine  hydrochlorate,  and  by  the  rose-red  'color 
produced  with  indol  and  sulphuric  acid. 

Artificial  silk  (made  from  nitrocellulose  or  by  dis- 
solving cotton  treated  with  soda  in  ammoniacal  copper 
solution)  is  differentiated  from  natural  silk  by  its 
slight  content  of  nitrogen  (less  than  1  per  cent.),  by 
its  insolubility  in  a  solution  of  10  grm.  copper  sulphate 
and  5  grm.  glycerin  in  100  cc.  water,  to  which  just  suffi- 
cient soda-lye  has  been  added  to  dissolve  the  precip- 
itate it  causes,  and  also  by  its  rapid  and  complete  com- 
bustion when  brought  into  contact  with  a  flame. 

Coloring-matter. — The  testing  for  and  differentiation 
of  the  individual  dyes,  of  which  many  hundreds  are 
used  in  practice,  can  not  here  be  described;  we  can 
only  restrict  our  observations  to  general  remarks,  and 
for  the  rest  refer  to  Gnehm's  "Taschenbuch  "  and  his 


DYEING.  123 

treatise  in  Vol.  Ill  of  Chem.-Techn.  Untersuchungs- 
methoden. 

Inorganic  dyes  are  examined  by  chemical  methods, 
and  by  practical  comparisons  with  a  sample  of  known 
properties,  the  "'type  "  or  standard.  Both  are  trit- 
urated with  linseed-oil,  with  the  addition  of  white  lead 
or  zinc  white,  and  compared  on  a  marble  slab ;  in  the 
case  of  dyes  for  printing  fabrics,  comparisons  between 
the  "type ''  and  sample  are  made  on  cotton. 

Organic  dyes  are  always  examined  by  means  of  test 
dyes.  First,  however,  it  is  necessary  to  gain  some 
idea  as  to  which  one  of  the  four  following  groups  the 
dye  in  question  belongs: 

1.  Direct-dyeing  cotton  dyes  are  fixed  on  the  fiber  by 
boiling  a  small  piece  of  cotton  rag  or  a  skein  with  the 
addition  of  a  little  soap,  soda,  or  sodium  phosphate, 
and  then  washing  with  water.    The  dyes  belonging  to 
the  other  classes  when  thus  treated  impart  no,  or  almost 
no,  color  to  the  fiber. 

2.  Basic  dyes  are  but  seldom  fixed  on  wool,  but  silk  is 
frequently  dyed  with  them.    They  dye  animal  fibers  (and 
wool  also)  even  without  a  mordant,  but  cotton  only  when 
it  is  tannated,  i.e.,  when  treated  with  a  tanning  sub- 
stance.   In  testing  whether  the  dye  is  suitable  for  use  on 
silk,  an  examination  must  be  made  as  to  whether  it  is  to 
be  used  in  a  neutral  or  acid  bath,  or  whether  the  dyeing 
is  to  be  effected  in  pure  water  or  the  raw-silk  bath,  and 
also  as  to  how  it  behaves  when  the  color  is  brightened. 

3.  Acid  dyes  do  not  fix  at  all,  or  almost  not  at  all, 
on  cotton,  nor  on  wool  in  a  neutral  bath,  but  do  so  very 


124  TECHNO-CHEMICAL  ANALYSIS. 

well  in  a  warm  bath  with  the  addition  of  sulphuric 
acid  or  acid  salts,  or  after  the  wool  has  first  been  treated 
with  sulphuric  acid,  alum,  or  potassium  bitartrate, 
after  which  the  dyeing  is  completed  in  a  boiling,  neu- 
tral bath.  Silk  is  dyed  without  any  such  preliminary 
treatment,  and  at  a  low  temperature. 

4.  Mordant-dyes  are  such  as  can  be  fixed  on  fibers 
only  in  the  form  of  their  metallic  lakes.  They  may  be 
recognized  by  the  fact  that  they  dye  neither  wool  nor 
cotton  in  acid,  neutral,  or  alkaline  bath,  but  do  so  after 
the  fabric  has  been  mordanted  with  solutions  of  alum,  etc. 
In  the  case  of  cotton,  pieces  are  used  that  have  been 
imprinted  with  various  mordants  in  parallel  rows.  Both 
the  wool  and  cotton  samples  are  then  dyed  with  heat, 
and  finally  treated  with  a  soap-bath  to  clear  the  color. 

After  having  ascertained  to  which  one  of  the  classes 
named  the  dye  belongs,  the  next  step  is  the 

Quantitative  Test  Dyeing. — For  this  purpose  there 
are  required,  besides  graduated  pipettes,  cylinders, 
and  flasks,  also  suitable  dye-vessels,  best  beakers  of 
porcelain  or  of  tinned  copper,  7.5  cm.  in  diameter  and 
14  cm.  in  height,  and  several  of  which  may  be  suspended 
at  one  time  in  a  copper  water-bath  by  means  of  a 
perforated  copper  plate  which  keeps"  the  beakers  a  few 
centimeters  from  the  bottom.  The  heating  is  done  by 
gas  or  with  a  steam-coil.  Where  higher  temperatures 
are  required,  glycerin,  oil,  or  the  like,  must  be  used 
instead  of  water.  For  suspending  the  skeins  or  trans- 
ferring them  from  one  dye-bath  to  another,  glass  rods 
are  used  which  are  "V«  or  "1  /"-shaped.  In  carrying 


DYEING.  125 

out  the  dyeing  tests,  it  is  essential  that  the  materials 
employed,  as  well  as  all  the  operations  to  be  made, 
approximate  as  closely  as  possible  to  those  prevailing 
in  manufacturing  on  the  large  scale,  but  which  is  not, 
of  course,  always  strictly-  possible.  The  fabric  in  this 
case  is  also  usually  to  be  compared  with  a  "type," 
and  both  are  to  be  treated  side  by  side  under  like  condi- 
tions. It  is  customary  to  dye  the  lighter  shades  of 
color,  because  these  are  more  readily  compared,  and 
the  dye-bath  is  then  exhausted  of  its  color  as  com- 
pletely as  possible.  As  a  rule,  1-per-cent.  solutions 
in  hot  water  (more  rarely  alcohol)  of  the  dye  to  be 
tested  and  the  "type,"  are  made,  and  calculations 
made  as  to  how  many  cubic  centimeters  are  required 
to  develop  a  1-  or  2-,  or  even  higher,  per  cent,  color 
on  a  weighed  quantity  of  fiber.  For  every  series  of 
tests,  like  quantities  by  weight  of  skeins  or  rags  are 
taken.  In  order  to  be  able  to  distinguish  the  various 
samples,  knots  are  tied  in  the  skeins,  and  holes  cut  in 
the  margins  of  the  rags. 

In  order  to  compare  the  dye  with  the  "type,"  like 
volumes  of  the  solutions  of  the  "type"  and  sample  are 
used  with  like  quantities  of  the  fiber.  After  a  little 
practice  quite  noticeable  increases  in  the  intensity  of 
coloration  are  recognized  even  before  the  end  of  the 
operation.  To  the  less  deeply  colored  sample  a  suffi- 
cient but  measured  volume  of  the  solution  of  the  dye 
is  added  until,  at  the  close  of  the  operation,  both  fabrics 
have  the  same  intensity  of  color.  In  making  the  com- 
parison both  skeins  must  be  drawn  from  the  bath  at 


126  TECHNO-CHEMICAL  ANALYSIS. 

the  same  time  in  order  that  they  may  be  observed  at 
the  same  degree  of  moistness;  the  comparison  must  be 
repeated  after  washing  with  water  and  drying,  and 
always  by  the  same  light. 

Usually,  "type"  samples  are  dyed  of  1,  1J,  and  2  per 
cent,  strength,  and  simultaneously,  with  samples  of  the 
products  to  be  tested,  whereby  it  is  generally  possible 
to  obtain  a  sample  that  will  correspond  to  one  of 
the  three  strengths  mentioned.  Should  this  not  happen 
to  be  the  case,  a  second,  or  at  worst  a  third,  trial  will 
suffice  to  afford  a  correct  sample,  whereupon  a  com- 
parison can  be  made  of  the  volumes  of  the  dye  solu- 
tions used  up.  In  making  the  comparison,  however, 
it  is  necessary  not  only  to  take  note  of  the  intensity 
of  the  color,  but  of  its  purity  also. 

If  the  dye  has  not  been  completely  used  up  in  the 
bath,  a  new  dyeing  experiment  must  be  made  with 
fresh  pieces  of  fabric,  using  the  partially  exhausted 
dye-bath,  and  the  supplementary  samples  compared. 
Fractional  dyeing  sometimes  permits  the  detection  of 
the  presence  of  several  dyes  or  foreign  substances. 

Silk  is  generally  dyed  in  the  skein  after  it  has  been 
boiled.  Frequently,  and  particularly  in  the  case  of 
acid  dyes,  a  bath  acidulated  with  acetic  or  sulphuric 
acid  suffices.  Often,  however,  "bast  soap"  is  used,  it 
being  first  added  to  the  bath,  then  the  necessary  quan- 
tity of  sulphuric  or  acetic  acid  to  "break"  the  bath, 
then  filling  up  with  water,  and  finally  adding  the  dye 
and  stirring  thoroughly.  In  the  case  of  basic  dyes,  a 
neutral  bath,  or  one  to  which  Marseilles  soap  has  been 


DYEING.  127 

added,  is  used;  for  substantive  cotton  dyes  a  neutral 
bath  with  5  to  15  per  cent,  of  sodium  phosphate  and 
5  per  cent,  of  soap  is  employed. 

The  silk  is  first  moistened  with  lukewarm  water,  then 
drawn  several  times  through  the  cold  or  lukewarm 
dye-bath,  then  removed,  the  bath  next  heated,  and 
the  dyeing  finally  completed  at  the  temperature  de- 
sired. The  silk  is  now  drawn  about  several  times  in 
another  bath  of  clean,  warm  water,  and  the  color 
cleared  by  placing  for  ten  minutes  in  water  acidulated 
very  weakly  with  sulphuric  or  acetic  acid.  After 
being  repeatedly  drawn  about  in  this  bath,  the  fabric 
is  wrung  out  and  dried.  Soft  water  must  be  used. 

Wool  is  taken  in  the  form  of  zephyr  yarn  or  flannel 
rags  thoroughly  freed  from  fat,  and  at  times  also  loose, 
but  in  this  case  great  care  must  be  exercised  in  order 
to  avoid  felting.  The  wool  is  thoroughly  moistened, 
the  greater  part  of  the  dye  fixed  on  at  about  50°  C., 
the  heat  gradually  raised  to  90°  to  95°  C.  while  con- 
stantly stirring,  the  bath  then  allowed  to  boil  gently 
for  fifteen  to  thirty  minutes  (with  alizarine  dyes,  from 
one  to  one  and  one-half  hours),  allowed  to  cool,  and  the 
fabric  then  washed  and  dried.  After  being  washed, 
the  skeins  are  weighted  with  sticks  and  hung  up,  and 
turned  occasionally  during  the  drying  in  order  to  avoid 
streaking. 

Acid  dyes  are  used  in  a  bath  to  which  is  added  from 
10  to  15  per  cent,  sodium  bisulphate;  the  addition  of 
alum  or  zinc  chloride  is  also  often  advantageous.  In 
the  case  of  dyes  that  "take  "  rapidly,  it  is  best  to  take 


128  TECHNO-CHEMICAL  ANALYSIS. 

at  first  only  2  to  5  per  cent,  acetic  acid  and  towards  the 
end  5  per  cent,  sulphuric  acid  (previously  diluted). 
Basic  dyes  are  fixed  on  without  any  addition  whatever; 
and  dyes  requiring  mordants,  after  a  preliminary  boiling 
with  the  latter  (potassium  bichromate,  alum,  tin  salt, 
ferrous  sulphate,  etc.,  with  various  additions). 

Cotton  is  dyed  in  the  form  of  well-boiled  and  washed 
hanks,  which,  in  the  case  of  light  colors,  must  also  be 
bleached.  The  substantive  dyes  (benzidine  dyes,  etc.) 
are  fixed  on  the  fiber  with  the  addition  of  from  20  to 
50  per  cent,  sodium  sulphate  or  sodium  chloride,  potas- 
sium carbonate,  sodium  (or  potassium)  silicate,  or 
sodium  phosphate.  More  salt  must  be  added  when 
the  dye  takes  with  difficulty  than  when  it  takes  rapidly. 
At  times  a  supplementary  treatment  with  copper  sul- 
phate, potassium  chromate,  and  the  like,  is  necessary. 
Insoluble  azo-dyes  are  fixed  on  the  fabric  by  "  coup- 
ling." In  the  case  of  the  basic  dyes,  the  cotton  is  first 
mordanted  with  tannin  and  tartar  emetic.  In  the  case 
of  the  true  mordant-dyes,  e.g.,  all  the  alizarine  dyes, 
the  cotton  is  first  treated  with  the  proper  metallic  salt 
(chromium,  alumina,  iron),  and  then  oiled  with  Turkey- 
red  oil  (5  to  10  per  cent,  oil  at  30°  to  40°  C.) ;  the  dyeing 
is  then  carried  to  completion  at  40°  to  50°  C.,  and  at 
times  even  at  higher  temperatures;  then  follow  boiling 
in  the  soap  bath  and  washing. 

In  making  tests  in  fabric  printing ,  a  small  printing- 
machine  must  be  employed,  and  the  pieces  treated  in  a 
manner  as  nearly  as  possible  like  that  carried  out  on 
the  large  scale. 


INDEX. 


PAGE 

Abel's  flash-point  apparatus 94 

Absorption-pipette,  compound 17 

for  liquids  and  solids 17 

Acetone,  detection  of 113 

Acetyl  number 99 

Acid,  carbolic,  crude 92 

examining 91 

preparations  of 92 

carbonic,  determining  in  bicarbonates 62 

determining  in  gases 11 

determining  in  illuminating-gas 82 

hydrochloric,  determining  impurities  in 61 

determining  in  vinegar 114 

examination  of 60,  61 

nitric,  determining  in  vinegar 114 

examination  of 55 

number,  determining 98 

oxalic,  determining  in  vinegar 114 

phosphoric,  determining  in  superphosphates 77 

sulphuric,  determining  impurities  in 52 

determining  in  mixtures  of  nitric  and  sulphuric 

acids 59 

determining  in  vinegar 114 

examination  of 49 

fuming,  examination  of 54 

Acids,  determining  in  wine 115 

mineral,  determining  in  vinegar 113 

total,  determination  in  calcination  gases 26 

determining  in  vinegar 113 

129 


130  INDEX. 

PAGE 

Alcohol,  determining  in  wine 115 

examining 107 

Alcoholometry 110 

Alkali,  total,  in  soaps,  determining 100 

Aluminium,  preparations,  examining 75 

sulphate,  examining 75 

Ammonia,  determining  in  illuminating-gas 84 

liquor,  examining 86 

-soda  process,  factory  control  of .' 63 

Ammonium  sulphate,  examining 87 

Analysis,  techno-chemical,  scope  of 1 

Anthracene,  examining 90 

Anthracite  coal,  examination  of 38 

Arsenic,  Marsh's  test  for 53 

Reinsch's  test  for 54 

Asbestos  filter,  Soxhlet's 105 

Azotometer,  Knop's 27 

Barley,  examining 116 

Baudouin's  test. . 99 

Bechi's  test 99 

Beer,  brewing 116 

examining 117 

Benzin,  examining 93 

Benzol,  determining  in  illuminating-gas 82 

Bicarbonate,  examining 66 

Bleaching  fluids,  examining 68 

Bomb-calorimeter 37 

Brandy,  examining 107 

Brown  coal,  examination  of 38 

Bunte's  burette 9 

Burette,  Bunte's 9 

KempeFs 15 

Orsat's 12 

Winkler's 7 

Calcimeter 29 

Calcium  carbide,  examining 87 

Calorimeter,  bomb- 37 

Candle-power  of  illuminating-gas,  determining 84 

Carbolic  acid,  see  Acid,  carbolic. 


INDEX.  131 


Carbonic  acid,  see  Acid,  carbonic. 

Carbonic  oxide,  determination  of,  in  gases 11 

Carnallit,  examining 71 

Cements,  examining 75 

Chancel's  sulphurimeter 44 

Chili  saltpeter,  examination  of 55 

Chlorates,  determining  in  superphosphates SO 

"  Chloride  of  Lime,"  see  Lime,  chlorinated. 

Chlorimetric  method,  Penot's '. 70 

Chlorine,  examining 68 

Clay,  examining 74,  75 

Coloring  matter,  testing  for 122 

Coal,  anthracite,  and  brown,  examination  of 38 

Coal-tar,  examining 87 

pitch,  examining 92 

Differentiating  coal-tar  benzol  from  petroleum,  benzin,  brown- 
coal  oils,  etc. 90 

Drehschmidt's  platinum  capillary 22 

Dyeing 121 

Dyes,  determining  in  wine V .......  116 

inorganic,  examining 123 

organic,  examining 123 

Engler's  apparatus  for  distilling  benzin 94 

viscosimeter 95 

Ethylene,  determining  in  illuminating-gas 82 

Extract,  determining  in  wine 115 

Fat,  total,  in  soaps,  determining 100 

Fats,  examining 97 

Fehling's  solution. 104 

Fermentation  test 108 

Fillers,  in  soaps,  determining 100 

Filter,  Soxhlet's  asbestos 105 

Flash-point  apparatus,  Abel's 94 

Pensky-Martin's 96 

determining 94 

Fuels,  examination  of 37 

Furfurol,  detection  of 113 

Fusel-oil,  determining Ill 

Fusible  cones,  Seger's. 74 


132  INDEX. 

PAGH 

Gas  analysis,  technical 7 

illuminating-,  examining , 82 

liquor,  examining 85 

-purifying  compound,  examining 84 

-sulphur,  examination  of 45 

-volumeter,  Lunge's 30, 34 

-volumetry 27 

Gases,  absorbable,  determining  very  small  quantities 26 

Reich's  method  of  determining 23 

collecting 5 

determining  by  combustion 19 

Glycerin,  examining 102 

Halphen's  test 99 

Hardness  of  water,  determination  of 40,  42 

Heat-values,  determination  of f 38 

Hehner's  number,  determining 97 

Hempel's  burette 15 

Hops,  examining 116 

Hubl's  number,  determining 98 

Hydrochloric  acid,  see  Acid,  hydrochloric. 

Hydrogen,  determining  in  gases. 14 

sulphide,  determining  in  illuminating-gas 83 

Illuminating-gas,  examining. 82 

Inversion  of  sugar 105 

Invert-sugar,  determining 104 

Iron,  determining  in  aluminium  colorimetrically 76 

determining  in  superphosphates 81 

Kainit,  examining 71 

Kerosene,  examining 94 

Knop's  azotometer 27 

Kottstorfer's  number,  determining 98 

Lime,  caustic,  examining. 67 

chlorinated,  examining 69 

determining  in  superphosphates 81 

Limestone,  examining 67 

Lubricating  oils,  examining 95 


INDEX.  133 

PAGE 

Lunge's  gas-volumeter 30,  34 

method  of  determining  nitrogen 56 

nitrometer 30 

Lyes,  electrolytic,  examining 64,  68 

for  sulphite  cellulose,  examination  of 49 

Malt,  determining  the  liquefying  power  of 109 

examining 108, 116 

Maltose,  determining 110 

Manganese  dioxide,  examining 66 

Manures,  artificial,  examining 77 

Marl,  examining 75 

Marsh's  test  for  arsenic 53 

Mash,  fermented,  examining 109 

sweet,  examining 109 

Methane,  determination  by  combustion 20, 22 

Molasses,  examining 108 

Naphtalin,  examining 90 

Nitric  acid,  examination  of 55-59 

Nitric  oxide,  determination  by  combustion 23 

Nitrogen,  determining  in  superphosphates 79 

nitrate-,  Ulsch's  method  of  determining 56 

Lunge's  method  of  determining 56 

Schlosing-Grandeau- Wagner's  method  of  determining  57 

Nitrometer,  Lunge's 30 

Nitrose,  examination  of < 48 

Nitrous  oxide,  determination  by  combustion 23 

Oils,  determining  foreign  constituents  in 99 

examining 97 

Orsat's  apparatus 12 

Palladium-asbestos  capillary,  Winkler's 21 

Penot's  chlorimetric  method 70 

Pensky-Martin's  flash-point  apparatus 96 

Perchlorate,  determining  in  niter 57 

Perchlorates,  determining  in  supjrphosphates 80 

Petroleum,  examining 93 

Pipette,  absorption-,  compound 17 

Pipettes,  absorption-,  for  liquids  and  solids 17 


134  INDEX. 

PAGE 

Platinum  capillary,  Drehschmidt's 22 

Polarizer,  Soleil-Ventzke-Scheibler 103 

Polarizing 104 

Potash,  examining 72 

Potassium  chloride,  examining 71, 72 

cyanide,  examining 73 

determining  in  superphosphates 81 

ferrocyanide,  examining 73 

salts 71 

Pyridine,  detection  of 113 

Pyrites,  examination  of 45 

Pyrometric  test 74 

Raw  material,  examination  of 1 

Reichert-Meissl  number 99 

Reich's  method  of  determining  absorbable  gases 23 

Reinsch's  test  for  arsenic.  .  „ 54 

Rock  salt,  examination  of 59 

Saccharine  juices,  examining 106 

Salt,  examination  of 59, 60 

Saltpeter,  examination  of 55 

Samples,  uniform,  preparation  of 3 

Saponification  number 98 

Schlosing-Grandeau-Wagner's  method  of  determining  nitrogen.  57 

Seger's  fusible  cones • 74 

Smoke-gases,  examination  of 39 

Soaps,  examining 100 

Soda-ash,  crude,  examination  of 62 

calcined,  examination  of 64 

caustic,  examining 65 

caustic,  factory  control  of 63 

crystal- 65 

examination  of 62 

Sodium  ferrocyanide 73 

Soxhlet  asbestos  filter 105 

Starch,  determining 107 

in  potatoes,  determining 108 

inverting 107 

Sugar-beets,  examining 102 

determining  in  wine 115 


INDEX.  135 

PAGE 

Sugar,  examining 102 

inverting 105 

Sulphate,  examination  of 59,  60 

Sulphur,  determining  in  illuminating-gas 83 

dioxide,  determination  in  calcination  gases 25 

examination  of .t 44 

Sulphuric  acid,  see  Acid,  sulphuric. 

Sulphurimeter,  Chancel's 44 

Superphosphates,  examining.. 77 

Table  comparing  specific  gravity,  degrees  Baume,  and  percent- 
age strength  of  sulphuric  acid 50 

Table  of  extract,  Windisch's 118 

showing  specific  gravity  and  percentage  strength  of  hy- 
drochloric acid 61 

showing    specific  gravity  and   percentage   strength    of 

nitric  acid 58 

showing  specific   gravity,    and    quantity    of    alcohol    in 

grammes  per  100  cc 13 

Tanning  extracts,  examining 119 

materials,  examining 119 

Tartrates,  determining  in  wine 116 

Test-dyeing,  quantitative 124 

Textile  fibers,  differentiating 121 

examining , 121 

Ulsch's  method  of  determining  nitrate  nitrogen 56 

Vinasse-potash,  examining 73 

Vinegar,  determining  mineral  acids  in 113 

determining  total  acid  in 113 

Viscosimeter,  Engler's 95 

Water,  determining  alkalinity  of 41 

determining  hardness  of 40,  42 

technical  analysis  of 39 

Weighing 4 

Wine,  determining  acids  in 115 

determining  alcohol  in 115 

determining  dyes  in 116 

determining  sugar  in 115 


136  INDEX. 

PAGE 

Wine,  determining  tartrates  in 116 

examining 115 

Winkler's  burette 7 

palladium-asbestos  capillary 21 

Wood-vinegar,  examining 114 

Wort,  examining 117 

£inc  blende,  examination  of 47 


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Pinner's  Introduction  to  Organic  Chemistry.     (Austen.) I2mo,  i  50 

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Riggs's  Elementary  Manual  for  the  Chemical  Laboratory 8vo,  i  25 

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Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Salkowski's  Physiological  and  Pathological  Chemistry.  (Orndorff.) 8vo.  2  30 

Schimpf  s  Text-book  of  Volumetric  Analysis I2mo,  2  50 

Essentials  of  Volumetric  Analysis iamo,  i  25 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

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Stockbridge's  Rocks  and  Soils 8vo,  2  50 

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Van  Deventer's  Physical  Chemistry  for  Beginners.     (Boltwood.) I2mo,  i  50 

*  Walke's  Lectures  on  Explosives 8vo,  4  oo 

Washington's  Manual  of  the  Chemical  Analysis  of  Rocks 8vo,  2  oo 

Wassermann's  Immune  Sera:  Haemolysins,  Cyto toxins,  and  Precipitins.     (Bol- 
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Wells's  Laboratory  Guide  in  Qualitative  Chemical  Analysis 8vo,  i   50 

Short  Course  in  Inorganic  Qualitative  Chemical  Analysis  for  Engineering 

Students i2mo,  i  50 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Wiechmann's  Sugar  Analysis Small  8vo,  2  50 

Wilson's  Cyanide  Processes i2mo,  i  50 

Chlorination  Process i2mo,  i  50 

Wulling's  Elementary  Course  in  Inorganic  Pharmaceutical  and  Medical  Chem- 
istry  ismo,  2  oo 

CIVIL  ENGINEERING. 

BRIDGES  AND    ROOFS.       HYDRAULICS.      MATERIALS   OF    ENGINEERING 
RAILWAY  ENGINEERING. 

Baker's  Engineers'  Surveying  Instruments i2ino,   3  oo 

Bixby's  Graphical  Computing  Table Paper  19^X24!  inches.        25 

**  Burr's  Ancient  and  Modern  Engineering  and  the  Isthmian  CanaL     (Postage* 

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Comstock's  Field  Astronomy  for  Engineers 8vo,    2  50 

Davis's  Elevation  and  Stadia  Tables 8vo,    i  oo 

Elliotts  Engineering  for  Land  Drainage 12010,    i  50 

Practical  Farm  Drainage xamot    i  oo 

Folwell's  Sewerage.     (Designing  and  Maintenance.) 8vo,    3  oo 

Freitag's  Architectural  Engineering.     2d  Edition  Rewritten 8vo     3  50 

French  and  Ives's  Stereotomy 8vo,    2  50 

Goodhue's  Municipal  Improvements 1 2 mo,    i  75 

Good  rich*  s  Economic  Disposal  of  Towns'  Refuse 8vo,    3  50 

Gore's  Elements  of  Geodesy 8vo,    2  50 

Hayford's  Text-book  of  Geodetic  Astronomy 8vo,    3  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,   2  50 

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Howe's  Retaining  Walls  for  Earth i2mo,  i  25 

Johnson's  (J.  B.)  Theory  and  Practice  01  Surveying Small  8vo,  4  oo 

Johnson's  (L.  J.)  Statics  by  Algebraic  and  Graphic  Methods 8vo,  2  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.)  i2tno,  200 

Mahan's  Treatise  on  Civil  Engineering.    (1873.)    (Wood.) , STO.  s  oo 

•  Descriptive  Geometry 8vo,  i  50 

Merriman's  Elements  of  Precise  Surveying  and  Geodesy 8vo,  2  50 

Elements  of  Sanitary  Engineering 8vo,  2  oo 

Merriman  and  Erooks's  Handbook  for  Surveyors i6mo,  morocco,  2  co 

Nugent's  Plane  Surveying 8vo  3  50 

Ogden's  Sewer  Design tamo,  2  oo 

Patton's  Treatise  on  Civil  Engineering. 8vo  half  leather,  7  50 

Reed's  Topographical  Drawing  and  Sketching 4to,  5  oo 

Rideal's  Sewage  and  the  Bacterial  Purification  of  Sewage 8vo,  3  50 

Siebert  and  Biggin's  Modern  Stone-cutting  and  Masonry 8vo ,  i  50 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo,  250 

Sondericker's  Graphic  Statics,  with  Applications    to  Trusses.  Beams,  and 

Arches -8vo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete  .Plain  and  Reinforced.    (In  press.) 

•  Trautwine's  Civil  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture.   8vo,  5  oo 

Sheep,  5  5° 

Law  of  Contracts 8vo,  3  oo 

Warren's  Stereotomy — Problems  in  Stone-cutting 8vo,  2  50 

Webb's  Problems  in  the  Use  and  Adjustment  of  Engineering  Instruments. 

1 6mo,  morocco,  i  25 

•  Wheeler's  Elementary  Course  of  Civil  Engineering 8vo,  4  oo 

Wilson's  Topographic  Surveying 8vo,  3  so 

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Boiler's  Practical  Treatise  on  the  Construction  of  Iron  Highway  Bridges.  .8vo,  2  oo 

•  Thames  River  Bridge 4to,  paper,  5  oo 

Burr's  Course  on  the  Stresses  in  Bridges  and  Roof  Trusses,  Arched  Ribs,  and 

Suspension  Bridges 8vo,  3  50 

Du  Bois's  Mechanics  of  Engineering.     VoL  II Small  4to,    i  o  oo 

Foster's  Treatise  on  Wooden  Trestle  Bridges 4to,  5  oo 

Fowler's  Coffer-dam  Process  for  Piers : 8vo,  2  50 

Ordinary  Foundations 8vo,  3  50 

Greene's  Roof  Trusses 8vo,  i  25 

Bridge  Trusses 8vo,  2  50 

Arches  in  Wood,  Iron,  and  Stone 8>o,  2  50 

Howe's  Treatise  on  Arches 8vo,  4  oo 

Design  of  Simple  Roof-trusses  in  Wood  and  Steel 8vo,  2  oo 

JohnsoSJlBryan,  and  Turneaure's  Theory  and  Practice  in  the  Designing  of 

Modern  Framed  Structures Small  4to,    10  oo 

Merriman  and  Jacoby's  Text-book  on  Roofs  and  Bridges: 

Part  I. — Stresses  in  Simple  Trusses 8vo,  2  50 

Part  IL— Graphic  Statics 8vo,  2  50 

Part  III,— Bridge  Design.    4th  Edition,  Rewritten 8vo,  2  50 

Part  IV. — Higher  Structures 8vo,  2  50 

Morison's  Memphis  Bridge 4to>   10  oo 

Waddell's  De  Pontibus,  a  Pocket-book  for  Bridge  Engineers. . .  i6mo.  morocco>  3  oo 

Specifications  for  Steel  Bridges lamo,  i  25 

Wood's  Treatise  on  the  Theory  of  the  Construction  of  Bridges  and  Roofs. 8vo,  2  oo 
Wright's  Designing  of  Draw-spans: 

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Two  parts  in  one  volume 8yo»  3  SO 

6 


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Orifice.    (Trautwine.) 8vo,  2  oo 

Bovey's  Treatise  on  Hydraulics 8vo,  5  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Diagrams  of  Mean  Velocity  of  Water  in  Open  Channels paper,  i  50 

Coffin's  Graphical  Solution  of  Hydraulic  Problems i6mo,  morocco,  2  50 

Flather's  Dynamometers,  and  the  Measurement  of  Power ismo,  3  oo 

Folwell's  Water-supply  Engineering 8vo,  4  oo 

Frizell's  Water-power.. ... 8vo,  5  oo 

Fuertes's  Water  and  Public  Health lamo,  i   50 

Water-filtration  Works I2mo,  2  50 

Ganguillet  and  Kutter's  General  Formula  for  the  Uniform  Flow  of  Water  in 

Rivers  and  Other  Channels.     (Hering  and  Trautwine.) 8vo.  4  oo 

Hazen's  Filtration  of  Public  Water-supply 8vo,  3  oo 

Hazlehurst's  Towers  and  Tanks  for  Water-works 8vo,  2  50 

Herschel's  115  Experiments  on  the  Carrying  Capacity  of  Large,  Riveted,  Metal 

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Mason's   Water-supply.    (Considered   Principally  from   a   Sanitary  Stand- 
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Merriman's  Treatise  on  Hydraulics,     gth  Edition,  Rewritten 8vo,  5  oo 

*  Michie's  Elements  of  Analytical  Mechanics 8vo,  4  oo 

Schuyler's  Reservoirs  for  Irrigation,  Water-power,  and  Domestic  Water- 
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Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Wegmann's  Design  and  Construction  of  Dams 4to,  5  oo 

Water-supply  of  the  City  of  New  York  from  1658  to  1895 4to,  10  oo 

Weisbach's  Hydraulics  and  Hydraulic  Motors.     (Du  Bois.) 8vo,  5  oo 

Wilson's  Manual  of  Irrigation  Engineering Small  8vo,  4  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines 8vo,  2  50 

Elements  of  Analytical  Mechanics 8vo,  3  oo 

MATERIALS  OP  ENGINEERING. 

Baker's  Treatise  on  Masonry  Construction 8vo,  5  oo 

Roads  and  Pavements 8vo,  5  oo 

Black's  United  States  Public  Works Oblong  4to,  5  oo 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  750 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.     6th  Edi- 
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Byrne's  Highway  Construction 8vo,  5  oo 

Inspection  of  the  Materials  and  Workmanship  Employed  in  Construction. 

i6mo,  3  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Du  Bois's  Mechanics  of  Engineering.    Vol.  I Small  4to,  7  50 

Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Fowler's  Ordinary  Foundations 8vo,  3  50 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.)    2  vols. 8vo,  7  50 

Merrill's  Stones  for  Building  and  Decoration 8vo,  5  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials i2mo,  i  oo 

Metcalf's  Steel.     A  Manual  for  Steel-users i2mo,  2  oo 

Patton's  Practical  Treatise  on  Foundations 8vo,  5  oo 

Richey's  Handbook  for  Building  Superintendents  of  Construction.     (In  press.) 

Rockwell's  Roads  and  Pavements  in  France I2mo,  i  25 

7 


Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines I2mo,  i  oo 

Snow's  Principal  Species  of  Wood 8vo,  3  50 

Spalding's  Hydraulic  Cement I2mo,  2  oo 

Text-book  on  Roads  and  Pavements i2mo,  2  oo 

Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced.     (In 

press.) 

Thurston's  Materials  of  Engineering.     3  Parts 8vo,  8  oo 

Part  1. — Non-metallic  Materials  of  Engineering  and  Metallurgy 8vo,  2  oo 

Part  II. — Iron  and  Steel 8vo,  3  50 

Part  III. — A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

Thurston's  Text-book  of  the  Materials  of  Construction 8vo,  5  oo 

Tillson's  Street  Pavements  and  Paving  Materials 8vo,  4  oo 

Waddell's  De  Pontibus.     (A  Pocket-book  for  Bridge  Engineers.) .  .  i6mo,  mor.,  3  oo 

Specifications  for  Steel  Bridges i2mo,  i  25 

Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials,  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,  2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,  3  oo 

Wood's  (M.  P.)  Rustless  Coatings :    Corrosion  and  Electrolysis  of  Iron  and 

Steel 8vo,  4  oo 

RAILWAY  ENGINEERING. 

Andrews's  Handbook  for  Street  Railway  Engineers 3x5  inches,  morocco,  i  25 

Berg's  Buildings  and  Structures  of  American  Railroads 4to,  5  oo 

Brooks's  Handbook  of  Street  Railroad  Location i6mo,  morocco,  i  50 

Butts's  Civil  Engineer's  Field-book i6mo,  morocco,  2  50 

Crandall's  Transition  Curve i6mo,  morocco,  i  50 

Railway  and  Other  Earthwork  Tables 8vo,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.     i6mo,  morocco,  5  oo 

Dredge's  History  of  the  Pennsylvania  Railroad:  (1879) Paper,  5  on 

*  Drinker's  Tunneling,  Explosive  Compounds,  and  Rock  Drills,  4to,  half  mor.,  25  oo 

Fisher's  Table  of  Cubic  Yards Cardboard,  25 

Godwin's  Railroad  Engineers'  Field-book  and  Explorers'  Guide ....  i6mo,  mor.,  2  50 

Howard's  Transition  Curve  Field-book i6mo,  morocco,  i  50 

Hudson's  Tables  for  Calculating  the  Cubic  Contents  of  Excavations  and  Em- 
bankments  8vo,  i  oo 

Molitor  and  Beard's  Manual  for  Resident  Engineers i6mo,  i  oo 

Nagle's  Field  Manual  for  Railroad  Engineers. i6mo,  morocco,  3  oo 

Philbrick's  Field  Manual  for  Engineers i6mo,  morocco,  3  oo 

Searles's  Field  Engineering i6mo,  morocco,  3  oo 

Railroad  Spiral i6mo,  morocco,  i  50 

Taylor's  Prismoidal  Formulae  and  Earthwork 8vo,  i  50 

*  Trautwine's  Method  ot  Calculating  the  Cubic  Contents  of  Excavations  and 

Embankments  by  the  Aid  of  Diagrams 8vo,  2  oo 

The  Field  Practice  of  Laying  Out  Circular  Curves  for  Railroads. 

1 2 mo,  morocco,  2  50 

Cross-section  Sheet Paper,  25 

Webb's  Railroad  Construction.     2d  Edition,  Rewritten i6mo,  morocco,  5  oo 

Wellington's  Economic  Theory  of  the  Location  of  Railways Small  8vo,  5  oo 

DRAWING. 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "       Abridged  Ed 8vo,  i  50 

Coolidge's  Manual  of  Drawing 8vo,  paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  Engi- 
neers  Oblong  4to.  2  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

8 


Hill's  Text-book  on  Shades  and  Shadows,  and  Perspective 8vo,  2  oo 

Jamison's  Elements  of  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I. — Kinematics*of  Machinery 8vo,  i  50 

Part  II. — Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

MacCord's  Elements  of  Descriptive  Geometry 8vo,  3  oo 

Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

Mahan's  Descriptive  Geometry  and  Stone-cutting 8vo,  i  50 

Industrial  Drawing.     (Thompson.) 8vo,  3  50 

Moyer's  Descriptive  Geometvy.     (In  press.') 

Reed's  Topographical  Drawing  and' Sketching 4to,  5  oo 

Reid's  Course  in  Mechanical  Drawing 8vo,  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design.  .8vo,  3  oo 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Manual  of  Topographical  Drawing.     (McMillan.) 8vo, 

Warren's  Elements  of  Plane  and  Solid  Free-hand  Geometrical  Drawing. .  I2mo, 

Drafting  Instruments  and  Operations i2mo, 

Manual  of  Elementary  Projection  Drawing i2mo, 

Manual  of  Elementary  Problems  in  the  Linear  Perspective  of  Form  and 

Shadow i2mo,  oo 

Plane  Problems  in  Elementary  Geometry 12010,  25 

Primary  Geometry i2mo,  75 

Elements  of  Descriptive  Geometry,  Shadows,  and  Perspective 8vo,  3  50 

General  Problems  of  Shades  and  Shadows 8vo  3  oo 

Elements  of  Machine  Construction  and  Drawing 8vo,  •  7  50 

Problems,  Theorems,  and  Examples  in  Descriptive  Geometry 8vo,  2  50 

Weisbach's  Kinematics  and   the   Power   of  Transmission.     (Hermann   and 

Klein.) 8vo,  5  oo 

Whelpley's  Practical  Instruction  in  the  Art  of  Letter  Engraving 12 mo,  2  oo 

Wilson's  (H.  M.)  Topographic  Surveying 8vo,  3  50 

Wilson's  (V.  T.)  Free-hand  Perspective 8vo,  2  50 

Wilson's  (V.  T.)  Free-hand  Lettering 8vo,  i  oo 

Woolf's  Elementary  Course  in  Descriptive  Geometry Large  8vo,  3  oo 

ELECTRICITY  AND   PHYSICS. 

Anthony  and  Brackett's  Text-book  of  Physics.     (Magie.) Small  8vo,  3  oo 

Anthony's  Lecture-notes  on  the  Theory  of  Electrical  Measurements i2mo,  i  oo 

Benjamin's  History  of  Electricity 8vo,  3  oo 

Voltaic  Cell 8vo,  3  oo 

Classen's  Quantitative  Chemical  Analysis  by  Electrolysis.     (Boltwood.).  .8vo,  3  oo 

Crehore  and  Squier's  Polarizing  Photo-chronograph 8vo,  3  oo 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .  i6mo,  morocco,  5  oo 
Dolezalek's    Theory    of    the    Lead    Accumulator    (Storage    Battery).     (Von 

Ende.) i2mo,  2  50 

Duhem's  Thermodynamics  and  Chemistry.     (Burgess.) 8vo,  4  oo 

Flather's  Dynamometers,  and  the  Measurement  of  Power I2mo,  3  oo 

Gilbert's  De  Magnete.     (Mottelay.) 8vo,  2  50 

Hanchett's  Alternating  Currents  Explained i2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors) i6mo,  morocco,  2  50 

Holman's  Precision  of  Measurements 8vo,  2  oo 

Telescopic  Mirror-scale  Method,  Adjustments,  and  Tests Large  8vo,  75 

Landauer's  Spectrum  Analysis.    (Tingle. )...... 8vo,  3  oo 

Le  Chate Her 's  High-temperature  Measurements.  (Boudouard — Burgess.  )i2mo  3  oo 

LoVs  Electrolysis  and  EJectrosynthesis  of  Organic  Compounds.  (Loreoz.)  lamo,  i  oo 

9 


*  Lyons's  Treatise  on  Electromagnetic  Phenomena.     Vo Is.  I.  and  H.  8vo,  each,  6  oo 

*  Michie.     Elements  of  Wave  Motion  Relating  to  Sound  and  Light 8vo,  4  oo 

Niaudet's  Elementary  Treatise  on  Electric  Batteries.     (Fishoack. ) i2mo,  2  50 

*  Rosenberg's  Electrical  Engineering.    (Haldane  Gee — Kinzbrunner.) . . .  .8vo,  i  50 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.     VoL  L 8vo,  2  50 

Thurston's  Stationary  Steam-engines 8vo,  2  50 

*  Tillman's  Elementary  Lessons  in  Heat 8vo,  i  50 

Tory  and  Pitcher's  Manual  of  Laboratory  Physics Small  8vo,  2  oo 

Ulke'.s  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

LAW. 

*  Davis's  Elements  of  Law 8vo,    2  50 

*  Treatise  on  the  Military  Law  ot  United  States 8vo,    7  oo 

Sheep,  7  50 

Manual  for  Courts-martial i6mo,  morocco,  i  50 

Wait's  Engineering  and  Architectural  Jurisprudence 8vo,  6  oo 

Sheep,  6  50 

Law  of  Operations  Preliminary  to  Construction  in  Engineering  and  Archi- 
tecture     8vo,  5  oo 

Sheep,  5  50 

Law  of  Contracts 8vo,  3  oo 

Winthrop's  Abridgment  of  Military  Law lamo,  2  50 

MANUFACTURES. 

Bernadou*s  Smokeless  Powder — Nitro-cellulose  and  Theory  of  the  Cellulose 

Molecule i2mo,  2  50 

Holland's  Iron  Founder I2mo,  2  50 

"  The  Iron  Founder,"  Supplement. 12010,  2  50 

Encyclopedia  of  Founding  and  Dictionary  of  Foundry  Terms  Used  in  the 

Practice  of  Moulding i2mo,  3  oo 

Eissler's  Modern  High  Explosives 8vo,  4  oo 

Effront's  Enzymes  and  their  Applications.     (Prescott. ) 8vo  3  oo 

Fitzgerald's  Boston  Machinist i8mo,  i  oo 

Ford's  Boiler  Making  for  Boiler  Makers i8mo,  i  oo 

Hopkins's  Oil-chemists'  Handbook 8vo,  3  oo 

Keep's  Cast  Iron 8vo,  2  50 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control.     (In  preparation.) 

Matthews's  The  Textile  Fibres 8vo,  3  50 

Metcalf's  SteeL    A  Manual  for  Steel-users i2mo,  2  oo 

Metcalfe's  Cost  of  Manufactures— And  the  Administration    of  Workshops, 

Public  and  Private x 8vo,  5  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Morse's  Calculations  used  in  Cane-sugar  Factories. i6mo,  morocco,  i  50 

*  Reisig's  Guide  to  Piece-dyeing 8vo,   25  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  3  oo 

Spalding's  Hydraulic  Cement i2mo,  2  oo 

Spencer's  Handbook  for  Chemists  of  Beet-sugar  Houses i6mo,  morocco,  3  oo 

Handbook  for  Sugar  Manufacturers  and  their  Chemists.. .  i6mo  morocco,    2  oo 
Taylor  and  Thompson's  Treatise  on  Concrete,  Plain  and  Reinforced.     (In 

press.) 

Thorston's  Manual  of  Steam-boilers,  their  Designs,  Construction  and  Opera- 
tion  8vo,    5  oo 

*  Walke's  Lectures  on  Explosives 8vo,    4  oo 

West's  American  Foundry  Practice i2mo,    2  50 

Moulder's  Text-book iamo.   2  50 

10 


Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Woodbury's  Fire  Protection  of  Mills 8vo,  2  50 

Wood's  Rustless  Coatings:  Corrosion  and  Electrolysis  of  Iron  and  Steel. .  .8vo,  4  oo 

MATHEMATICS. 

Baker's  Elliptic  Functions 8vo,  i  50 

*  Bass's  Elements  of  Differential  Calculus i2mo,  4  oo 

Briggs's  Elements  of  Plane  Analytic  Geometry I2mo,  i  oo 

Compton's  Manual  of  Logarithmic  Computations izmo,  i  50 

Davis's  Introduction  to  the  Logic  of  Algebra 8vo,  i  50 

*  Dickson's  College  Algebra Large  i2mo,  i  50 

*  Answers  to  Dickson's  College  Algebra 8vo,  paper,  25 

*  Introduction  to  the  Theory  of  Algebraic  Equations   Large  i2mo,  i  25 

Halsted's  Elements  of  Geometry 8vo,  i  75 

Elementary  Synthetic  Geometry 8vo,  i  50 

Rational  Geometry I2mo, 

*  Johnson's  (J.  B.)  Three-place  Logarithmic  Tables:  Vest-pocket  size,  .paper,  15 

100  copies  for  5  oo 

*  Mounted  on  heavy  cardboard,  8  X 10  inches,  25 

10  copies  for  2  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  Differential  Calculus.  .  .Small  8vo,  3  oo 

Johnson's  (W.  W.)  Elementary  Treatise  on  the  Integral  Calculus.  .  Small  8vo,  i  50 

Johnson's  (W.  W.)  Curve  Tracing  in  Cartesian  Co-ordinates i2mo,  i  oo 

Johnson's  (W.  W.)  Treatise  on  Ordinary  and  Partial  Differential  Equations. 

Small  8vo,  3  50 

Johnson's  (W.  W.)  Theory  of  Errors  and  the  Method  of  Least  Squares.  .  i2mo,  i  50 

*  Johnson's  (W.  W.)  Theoretical  Mechanics i2mo,  3  oo 

Laplace's  Philosophical  Essay  on  Probabilities.     (Truscott  and  Emory.)  i2mo,  2  oo 

*  Ludlow  and  Bass.     Elements  of  Trigonometry  and  Logarithmic  and  Other 

Tables '. 8vo,  3  oo 

Trigonometry  and  Tables  published  separately Each,  2  oo 

*  Ludlow's  Logarithmic  and  Trigonometric  Tables 8vo,  i  oo 

Maurer's  Technical  Mechanics 8vo,  4  oo 

Merriman  and  Woodward's  Higher  Mathematics 8vo,  5  oo 

Merriman's  Method  of  Least  Squares 8vo,  2  oo 

Rice  and  Johnson's  Elementary  Treatise  on  the  Differential  Calculus  .Sm.,  8vo,  3  oo 

Differential  and  Integral  Calculus.     2  vols.  in  one Small  8vo,  2  50 

Wood's  Elements  of  Co-ordinate  Geometry 8vo,  2  oo 

Trigonometry:  Analytical,  Plane,  and  Spherical I2mo,  i  oo 

MECHANICAL   ENGINEERING. 
MATERIALS  OF  ENGINEERING,  STEAM-ENGINES  AND  BOILERS. 

Bacon's  Forge  Practice i2mo,  i  50 

Baldwin's  Steam  Heating  for  Buildings i2mo,  2  50 

Barr's  Kinematics  of  Machinery 8vo,  2  50 

*  Bartlett's  Mechanical  Drawing 8vo,  3  oo 

*  "                «•                        Abridged  Ed 8vo,  i  50 

Benjamin's  Wrinkles  and  Recipes i2mo,  2  oo 

Carpenter's  Experimental  Engineering .8vo,  6  oo 

Heating  and  Ventilating  Buildings 8vo,  4  oo 

Gary's  Smoke  Suppression  in  Plants  using  Bituminous  CoaL     (In  prep- 
aration.) 

Clerk's  Gas  and  Oil  Engine Small  8vo,  4  oo 

Coolidge's  Manual  of  Drawing .8vo,    paper,  i  oo 

Coolidge  and  Freeman's  Elements  of  General  Drafting  for  Mechanical  En- 
gineers  Oblong  4to,  2  50 

11 


Cromwell's  Treatise  on  Toothed  Gearing izmo,  i  50 

Treatise  on  Belts  and  Pulleys i2mo,  i  50 

Durley's  Kinematics  of  Machines 8vo,  4  oo 

Flather's  Dynamometers  and  the  Measurement  of  Power 12 mo,  3  oo 

Rope  Driving I2mo,  2  oo 

Gill's  Gas  and  Fuel  Analysis  for  Engineers , i2mo,  i  25 

Hall's  Car  Lubrication i2mo,  i  oo 

Bering's  Ready  Reference  Tables  (Conversion  Factors). . i6mo,  morocco,  2  50 

Button's  The  Gas  Engine 8vo.  5  oo 

Jamison's  Mechanical  Drawing 8vo,  2  50 

Jones's  Machine  Design: 

Part  I. — Kinematics  of  Machinery Svo,  i  50 

Part  II. — Form,  Strength,  and  Proportions  of  Parts 8vo,  3  oo 

Kent's  Mechanical  Engineer's  Pocket-book i6mo,  morocco,  5  oo 

Kerr's  Power  and  Power  Transmission 8vo,  2  oo 

Leonard's  Machine  Shops,  Tools,  and  Methods.    (In  press.) 

MacCord's  Kinematics;  or,  Practical  Mechanism 8vo,  5  oo 

Mechanical  Drawing 4to,  4  oo 

Velocity  Diagrams 8vo,  i  50 

Mahan's  Industrial  Drawing.    (Thompson.) 8vo,  3  50 

Poole's  Calorific  Power  of  Fuels 8vo,  3  oo 

Reid's  Course  in  Mechanical  Drawing 8vo.  2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design. . 8vo,  3  oo 

Richards's  Compressed  Air izmo,  i  50 

Robinson's  Principles  of  Mechanism 8vo,  3  oo 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,  3  oo 

Smith's  Press-working  of  Metals 8vo,  .3  oo 

Thurston's  Treatise  on   Friction  and    Lost  Work  in   Machinery   and   Mill 

Work 8vo,  3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  xzmo,  i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing 870,  7  50 

Weisbach's  Kinematics  and  the  Power  of  Transmission.      Herrmann- 
Klein.) 8vo,  5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann — Klein.).  .8vo,  500 

Hydraulics  and  Hydraulic  Motors.     (Du  Bois.) Svo.  5  oo 

Wolff's  Windmill  as  a  Prime  Mover 8vo,  3  oo 

Wood's  Turbines Svo,  2  50 

MATERIALS  OF  ENGINEERING. 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo.  7  50 

Burr's  Elasticity  and  Resistance  of  the  Materials  of  Engineering.     6th  Edition 

Reset 8vo.  7  50 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

Johnson's  Materials  of  Construction Large  8vo,  6  oo 

Keep's  Cast  Iron 8vo,  2  50 

Lanza's  Applied  Mechanics 8vo,  7  50 

Martens's  Handbook  on  Testing  Materials.     (Henning.) 8vo,  7  50 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,  4  oo 

Strength  of  Materials   izmo,  i  oo 

Metcalf  s  SteeL     A  Manual  for  Steel-users i2mo  2  oo 

Sabin's  Industrial  and  Artistic  Technology  of  Paints  and  Varnish 8vo,  3  oo 

Smith's  Materials  of  Machines i2mo,  i  oo 

Thurston's  Materials  of  Engineering 3  vote  ,  Svo.  8  oo 

Part   n. — Iron  and  Steel Svo,  3  50 

Part  III. — A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents Svo  2  50 

TtXt-book  Of  the  Materials  of  Construction Svo.  5  oo 

12 


Wood's  (De  V.)  Treatise  on  the  Resistance  of  Materials  and  an  Appendix  on 

the  Preservation  of  Timber 8vo,    2  oo 

Wood's  (De  V.)  Elements  of  Analytical  Mechanics 8vo,    3  oo 

Wood's  (M.  P.)  Rustless  Coatings:  Corrosion  and  Electrolysis  of  Iron  and  Steel. 

8vo,    4  oo 


STEAM-ENGINES  AND  BOILERS. 

Carnot's  Reflections  on  the  Motive  Power  of  Hee.t.    (Thunrton.) i2nro,  i  50 

Dawson's  "Engineering"  and  Electric  Traction  Pocket-book.  .l6mo,  mor.,  5  oo 

Ford's  BoiJer  Making  for  Boiler  Makers i8mo,  i  oo 

Goss's  Locomotive  Spariss, 8vo,  2  oo 

Hemenway's  Indicator  Practice  and  Steam-engine  Economy i2mo,  2  oo 

Button's  Mechanical  Engineering  of  Power  Plants 8vo,  5  oo 

Heat  and  Heat-engines 8vo,  5  oo 

Kent's  Steam-boiler  Economy 8vo,  4  oo 

Kneass's  Practice  and  Theory  of  the  Injector 8vo,  i  50 

MacCord's  Slide-valves 8vo,  2  oo 

Meyer's  Modern  Locomotive  Construction 4to,  10  oo 

Peabody's  Manual  of  the  Steam-engine  Indicator izmo,  i  50 

Tables  of  the  Properties  of  Saturated  Steam  and  Other  Vapors 8vo,  i  oo 

Thermodynamics  of  the  Steam-engine  and  Other  Heat-engines 8vo.  5  oo 

Valve-gears  for  Steam-engines 8vo,  2  50 

Peabody  and  Miller's  Steam-boilers 8vo,  4  oo 

Pray'a  Twenty  Years  with  the  Indicator Large  8vo,  2  50 

Pupln's  Thermodynamics  of  Reversible  Cycles  in  Gases  and  Saturated  Vapors. 

(Osterberg.) zamo,  i  25 

Reagan's  Locomotives :  Simple,  Compound,  and  Electric i  amo,  2  50 

Rontgen's  Principles  of  Thermodynamics.     (Du  Bois.) 8vo,  5  oo 

Sinclair's  Locomotive  Engine  Running  and  Management 12010,  2  oo 

Smart's  Handbook  of  Engineering  Laboratory  Practice 12010,  2  50 

Snow's  Steam-boiler  Practice 8vo,  3  oo 

Spangler's  Valve-gears 8vo,  2  50 

Notes  on  Thermodynamics i2mo,  i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,  3  oo 

Thurston's  Handy  Tables 8vo,  i  50 

Manual  of  the  Steam-engine 2  vols. .  8vo,  10  oo 

Part  I. — History,  Structuce,  and  Theory 8vo,  6  oo 

Part  H.~— Design,  Construction,  and  Operation 8vo,  6  oo 

Handbook  of  Engine  and  Boiler  Trials,  and  the  Use  of  the  Indicator  and 

the  Prony  Brake 8vo,  5  oo 

Stationary  Steam-engines 8vo,  2  50 

Steam-boiler  Explosions  in  Theory  and  in  Practice 12 mo,  i  50 

Manual  of  Steam-boiler? ,  Their  Designs,  Construction,  and  Operation .  8vo,  5  oo 

Weisbach's  Heat,  Steam,  and  Steam-engines.     (Du  Bois.) 8vo,  5  oo 

Whitham's  Steam-engine  Design 8vo,  5  oo 

Wilson's  Treatise  on  Steam-boilers.     (Flather.) i6mo,  2  50 

Wood's  Thermodynamics  Heat  Motors,  and  Refrigerating  Machines 8vo,  4  oo 


MECHANICS    AND  MACHINERY. 


Barr's  Kinematics  of  Machinery 8vo,  2  50 

Bovey's  Strength  of  Materials  and  Theory  of  Structures 8vo,  7  50 

Chase's  The  Art  of  Pattern-making i2mo,  2  50 

ChordaL — Extracts  from  Letters I2mo,  2  oo 

Church's  Mechanics  of  Engineering 8vo,  6  oo 

13 


Church's  Notes  and  Examples  in  Mechanics 8vo,    2  oo 

Compton's  First  Lessons  in  Metal-working izmo,    i  50 

Compton  and  De  Groodt's  The  Speed  Lathe i2mo,    i  50 

Cromwell's  Treatise  on  Toothed  Gearing i2mo,    i  50 

Treatise  on  Belts  and  Pulleys .  i2mo,    i  50 

Dana's  Text-book  of  Elementary  Mechanics  for  the  Use  of  Colleges  and 

Schools i2mo,    i  50 

Dingey's  Machinery  Pattern  Making i2mo,    2  oo 

Dredge's  Record  of  the  Transportation  Exhibits  Building  of  the  World's 

Columbian  Exposition  of  1893 4to  half  morocco,   5  00 

Du  Bois's  Elementary  Principles  of  Mechanics: 

VoL     I. — Kinematics 8vo,    3  50 

Vol.   n. — Statics 8vo,    4  oo 

Vol.  m.— Kinetics 8vo,    3  50 

Mechanics  of  Engineering.     VoL  I Small  4to,      7  50 

VoL  n. Small  4to,    10  oo 

Durley's  Kinematics  of  Machines  8vo,       oo 

Fitzgerald's  Boston  Machinist i6mo, 

Flather's  Dynamometers,  and  the  Measurement  of  Power 12 mo, 

Rope  Driving xamo, 

Goss's  Locomotive  Sparks 8vo, 

Hall's  Car  Lubrication i2mo, 

Holly's  Art  of  Saw  Filing i8mo,        75 

*  Johnson's  (W.  W.)  Theoretical  Mechanics ' i2mo,    3  oo 

Johnson's  (L.  J.)  Statics  by  Graphic  and  Algebraic  Methods 8vo,    2  oo 

Jones's  Machine  Design: 

Part  I. — Kinematics  of  Machinery 8vo,    i  50 

Part  H.— Form,  Strength,  and  Proportions  of  Parts. 8vo,    3  oo 

Kerr's  Power  and  Power  Transmission 8vo,    2  oo 

Lanza's  Applied  Mechanics 8vo,    7  50 

Leonard  s  Machine  Shops,  Tools,  and  Methods.    (In  press.) 

MacCord's  Kinematics ;  or,  Practical  Mechanism 8vo ,    5  oo 

Velocity  Diagrams 8vo,    i  50 

Maurer's  Technical  Mechanics 8vo,    4  oo 

Merriman's  Text-book  on  the  Mechanics  of  Materials 8vo,   4  oo 

*  Michte's  Elements  of  Analytical  Mechanics 8vo,    4  oo 

Reagan's  Locomotives:  Simple,  Compound,  and  Electric tamo,   2  50 

Reid's  Course  in  Mechanical  Drawing 8vo,    2  oo 

Text-book  of  Mechanical  Drawing  and  Elementary  Machine  Design . .  8vo,    3  oo 

Richards's  Compressed  Air i2mo,    i  50 

Robinson's  Principles  of  Mechanism 8vo,    3  oo 

Ryan,  Norris,  and  Hoxie's  Electrical  Machinery.    Vol.1 8vo,   2  50 

Schwamb  and  Merrill's  Elements  of  Mechanism 8vo,    3  oo 

Sinclair's  Locomotive-engine  Running  and  Management Z2mo,    2  oo 

Smith's  Press-working  of  Metals 8vo,    3  oo 

Materials  of  Machines I2mo,    i  oo 

Spangler,  Greene,  and  Marshall's  Elements  of  Steam-engineering 8vo,   3  oo 

Thurston's  Treatise  on  Friction  and  Lost  Work  in  Machinery  and  Mill 

Work 8vo,   3  oo 

Animal  as  a  Machine  and  Prime  Motor,  and  the  Laws  of  Energetics .  i2mo,    i  oo 

Warren's  Elements  of  Machine  Construction  and  Drawing 8vo,    7  50 

Weisbach's    Kinematics    and    the  Power  of    Transmission.     (Herrmann — 

Klein.) 8vo,    5  oo 

Machinery  of  Transmission  and  Governors.     (Herrmann— Klein.). 8 vo,    5  oo 
Wood's  Elements  of  Analytical  Mechanics 8vo,    3  oo 

Principles  of  Elementary  Mechanics I2mo,    i  25 

Turbines 8vo,    2  50 

The  World's  Columbian  Exposition  of  1893 - 4to,    i  oo 

14 


METALLURGY. 

Egleston's  Metallurgy  of  Silver,  Gold,  and  Mercury: 

VoL  I.— Silver 8vo,  7  So 

VoL  H.— Gold  and  Mercury 8vo,  7  50 

**  Iles's  Lead-smelting.    (Postage  9  cents  additional.) xamo,  2  50 

Keep's  Cast  Iron 8vo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe 8vo,  i  50 

Le  Chatelier's  High-temperature  Measurements.  (Boudouard — Burgess.) .  12 mo,  3  oo 

Metcalf  s  SteeL    A  Manual  for  Steel-users i2mo,  2  oo 

Smith's  Materials  of  Machines i2mo,  i  oo 

Thurston's  Materials  of  Engineering.    In  Three  Parts 8vo,  8  oo 

Part  II. — Iron  and  Steel .* 8vo,  3  50 

Part  III.— A  Treatise  on  Brasses,  Bronzes,  and  Other  Alloys  and  their 

Constituents 8vo,  2  50 

dike's  Modern  Electrolytic  Copper  Refining 8vo,  3  oo 

MINERALOGY. 

Barringer's  Description  of  Minerals  of  Commercial  Value.    Oblong,  morocco,  2  50 

Boyd's  Resources  of  Southwest  Virginia 8vo,  3  oo 

Map  of  Southwest  Virginia Pocket-book  form,  2  oo 

Brush's  Manual  of  Determinative  Mineralogy.    (Penfield.) 8vo,  4  oo 

Chester's  Catalogue  of  Minerals 8vo,  paper,  i  oo 

Cloth,  i  25 

Dictionary  of  the  Names  of  Minerals 8vo,  3  50 

Dana's  System  of  Mineralogy. Large  8ro,  half  leather,    12  50 

First  Appendix  to  Dana's  New  "System  of  Mineralogy.".... Large 8vo,  i  oo 

Text-book  of  Mineralogy 8vo,  4  oo 

Minerals  and  How  to  Study  Them. ... « xamo,  50 

Catalogue  of  American  Localities  of  Minerals Large  8vo,  oo 

Manual  of  Mineralogy  and  Petrography i2mo,  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects i2mo,  oo 

Eakle's  Mineral  Tables. 8vo.  25 

Egleston's  Catalogue  of  Minerals  and  Synonyms 8vo,  50 

Hussak's  The  Determination  of  Rock-forming  Minerals.    (Smith.)  Small  Svo,  oo 

Merrill's  Non-metallic  Minerals:  Their  Occurrence  and  Uses. Svo,  4  oo 

*  Penfisld's  Notes  on  Determinative  Mineralogy  and  Record  of  Mineral  Tests. 

Svo,  paper,  o  50 
Rosenbusch's  Microscopical  Physiography  of  the  Rock-making  Minerals. 

(Iddings.) Svo,  5  oo 

*  TiUman's  Text-book  of  Important  Minerals  and  Docks Svo,  2  oo 

Williams's  Manual  of  Lithology Svo,  3  oo 

MINING. 

Beard's  Ventilation  of  Mines zamo,  2  50 

Boyd's  Resources  of  Southwest  Virginia Svo,  3  oo 

Map  of  Southwest  Virginia Pocket-book  form,  2  oo 

Douglas's  Untechnical  Addresses  on  Technical  Subjects 121110,  i  oo 

*  Drinker's  Tunneling,  Explosive  Compounds,  and  Rock  Drills. 

4to,  half  morocco,    25  oo 

Eissler's  Modern  High  Explosives Svo,  4  oo 

Fowler's  Sewage  Works  Analyses X2mo,  2  oo 

Goodyear 's  Coal-mines  of  the  Western  Coast  of  the  United  States 12  mo,  2  50 

Ihlseng's  Manual  of  Mining Svo,  4  oo 

**  Des's  Lead-smelting.     (Postage  oc.  additional) f X2mo,  2  50 

Kunhardt's  Practice  of  Ore  Dressing  in  Europe Svo,  i  50 

O'DriscolTs  Notes  on  the  Treatment  of  Gold  Ores Svo,  2  oo 

*  Walke's  Lectures  on  Explosives Svo,  4  oo 

Wilson's  Cyanide  Processes >. . . xamo,  i  50 

Chlorination  Process xamo,    i  50 

15 


Wilson's  Hydraulic  and  Placer  Mining tamo,  2  oo 

Treatise  on  Practical  and  Theoretical  Mine  Ventilation i2mo,  i   25 

SANITARY  SCIENCE. 

Folwell's  Sewerage.     (Designing,  Construction,  and  Maintenance.) 8vo,  3  oo 

Water-supply  Engineering 8vo,  4  oo 

Fuertes's  Water  and  Public  Health i2mo,  i  50 

Water-filtration  Works 12010,  2  50 

Gerhard's  Guide  to  Sanitary  House-inspection , i6mo,  i  oo 

Goodrich's  Economical  Disposal  of  Town's  Refuse Demy  8vo,  3  50 

Hazen's  Filtration  of  Public  Water-supplies 8vo,  3  oo 

Leach's  The  Inspection  and  Analysis  of  Food  with  Special  Reference  to  State 

Control 8vo,  7  50 

Mason's  Water-supply.     (Considered    Principally    from    a    Sanitary    Stand- 
point.)    3d  Edition,  Rewritten 8vo,  4  oo 

Examination  of  Water.     (Chemical  and  Bacteriological.) i2mo,  i  25 

Merriman's  Elements  of  Sanitary  Engineering 8vo,  2  oo 

Ogden's  Sewer  Design i2mo,  2  oo 

Prescott  and  Winslow's  Elements  of  Water  Bacteriology,  with  Special  Reference 

to  Sanitary  Water  Analysis i2mo,  i  25 

*  Price's  Handbook  on  Sanitation i2mo,  i  50 

Richards's  Cost  of  Food.     A  Study  in  Dietaries i2mo,  i  oo 

Cost  of  Living  as  Modified  by  Sanitary  Science i2mo,  i  oo 

Richards    and  Woodman's  Air,  Water,  and  Food   from  a  Sanitary  Stand- 
point  8vo,  2  oo 

*  Richards  and  Williams's  The  Dietary  Computer 8vo,  i  50 

Rideal's  Sewage  and  Bacterial  Purification  of  Sewage 8vo>  3  50 

Turneaure  and  Russell's  Public  Water-supplies 8vo,  5  oo 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo,  i  oo 

Whipple's  Microscopy  of  Drinking-water 8vo,  3  50 

Woodhull's  Notes  and  Military  Hygiene i6mo,  i  50 

MISCELLANEOUS. 

Emmons's  Geological  Guide-book  of  the  Rocky  Mountain  Excursion  of  the 

International  Congress  of  Geologists Large  8vo,  i  50 

Ferrel's  Popular  Treatise  on  the  Winds 8vo,  4  oo 

Haines's  American  Railway  Management i2mo  2  50 

Mott's  Composition,  Digestibility,  and  Nutritive  Value  of  Food.  Mounted  chart,  i  25 

Fallacy  of  the  Present  Theory  of  Sound i6mo,  i  oo 

Ricketts's  History  of  Rensselaer  Polytechnic  Institute,  1824-1894.  Small  8vo,  3  oo 

Rostoski's  Serum  Diagnosis.     (Bolduan.) i2mo,  i  oo 

Rotherham's  Emphasized  New  Testament Large  8vo,  2  oo 

Steel's  Treatise  on  the  Diseases  of  the  Dog 8vo,  3  50 

Totten's  Important  Question  in  Metrology 8vo,  2  50 

The  World's  Columbian  Exposition  of  1893 4to,  i  oo 

Von  Behring's  Suppression  of  Tuberculosis.     (Bolduan.) i2mo,  i  oo 

Worcester  and  Atkinson.     Small  Hospitals,  Establishment  and  Maintenance, 
and  Suggestions  for  Hospital  Architecture,  with  Plans  for  a  Small 

Hospital i2mo,  i  25 

HEBREW  AND  CHALDEE  TEXT-BOOKS. 

Green's  Grammar  of  the  Hebrew  Language 8vo,  3  oo 

Elementar.y  Hebrew  Grammar i2mo.  i  25 

Hebrew  Chrestomathy 8vo,  2  oo 

Gesenius's  Hebrew  and  Chaldee  Lexicon  to  the  Old  Testament  Scriptures. 

(Tregelles.) Small  4to,  half  morocco,  5  oo 

Letteris?fc  Hebrew  Bible 8vo,  2  25 

16 


I 


M.        «. 

OVERDUE. 


OCT  23  1932 

OCT    24   1932 


YB   16734 


":••:•;". :-.•'.••!:;-  n 
^M^/K' 


